If you played the ♣K, West will ruff and you will lose 2 more club tricks for down 1! If you played the ♣5 then you have made your contract. Remember that declarer first consideration is to make the contract. Here is why by not covering the ♣Q with the ♣K is the right play.  By ducking the ♣Q, regardless of how the clubs are divided the contract will be made.  By playing the ♣K if the opening lead is a singleton like this case then declarer will lose 2 additional club tricks and not make the contract.  Remember making the contract is first consideration.

At Trick 3 you ruff high winning the trick. You then cash two trump tricks and play three club tricks discarding a ♦  from dummy. So far you found out that East started with 2 spades, 3 clubs, 6 hearts and so must have only 2 diamonds.

So instead of finessing the ♦ Q you should play the ♦ A and return to your hand and play towards the ♦ Q which loses to the ♦ K.  However, East can only return a ♥  to give you a ruff and a sluff.  Your contract is made without having to finesse the ♦ Q.  It did not matter who had the ♦ K.  If West had it then your ♦ Q is good.

From the auction you know partner cannot have more than ♣A with your 9 HCP.  Partner also returned the ♣4 showing 3 cards remaining in ♣.  If you cash in all your clubs, declarer will discard the ♦10 on your clubs and no matter what you play after collecting your 4 clubs, the diamonds will no longer be blocked!  So, you needed to lead the ♦Q at trick four after playing your ♣Q on the ♣J.  It does not matter if declarer or dummy wins the trick. You have the ♥K which will be your re-entry in your hand to cash all your clubs.  The contract will be down 1. 

Declarer Play

Declarer wins ♠K with the ♠A but realizes that a trick will be lost to the ♦A and maybe a ♠  so we need to get rid of the ♠ in dummy. If you use the heart suit to shed the ♠ loser you probably went down 1!  You need to recognize the lead of a 4^th round of hearts by either defender would put the slam in danger. So, after playing the ♥  J-A-K the next thing to do is to play the ♣AK and to drop the ♥Q on the second ♣. Since you have all the high trumps whoever has the ♦A and maybe the heart cannot sink your slam.  If it is played you would play a high ♦ and draw the last trump and the slam is home.  Had you kept your ♥Q the other defender would have ruffed it.

It was important to recognize the treat of playing 3 rounds of ♥ .

Plan at Trick One

If you played the ♦K at Trick Two hoping to ruff your losing ♦  in dummy your contract went down!

Play ♥K and when West plays the ♥10, and just in case East had started with the singleton ♦ , lead a ♠ to your ♠A and then lead a ♦ toward your ♦K. East did not ruff but discarded a ♠, so you won with your ♦K.  If East would have ruff it would have been much easier to make the contract.  Now you lead a third ♦ and ruff with dummy’s ♥A. You ruff a ♠  and then play the fourth ♦ which is ruffed by dummy and overruffed by East to produce the only trick for the opponents.  In this case it was prudent to be cautious and not to play the ♦K at Trick Two just in case East had started with a singleton.

Plan at Trick 1

If you played the ♣K at Trick 1 you probably went down!  East will win with ♣A and return a club. Now West will switch to a diamond and ultimately you will lose 2 diamonds and go down 1 trick.

If you held back your ♣K, East will likely continue the clubs where the second trick will be won by East.  Whatever East plays, likely a spade you will win with the ♠Q and play two rounds of trumps ending in your hand. 

You will play the ♠AK where dummy will discard a ♦5  on the second spade.  Now you are set up to play a diamond toward dummy and play the ♦10 which will be won by East.  East can only exit a spade to give you a ruff and a sluff or a diamond into your ♦AJ.  You will then have 10 tricks.

Delaying Trump

Did you win the lead with the ♥A and try the ♠Q finesse? Immediately you went down one! West will lead back the ♥J.

You realize that you have losers in each suit. So, the plan should be to try to create a winner in a side suit;  delaying the play of the trump suit is best. You win the lead with the ♥K and play a small ♣  toward the ♣Q but West will go up with the ♣K and return the ♥J taken by the A. Now declarer can lead a ♠ to the ♠A (forsaking the finesse for the success of the contract). Play the ♣A to discard a ♥ and ruff with ♠9 declarer's last ♥ . Now play the trump suit and West gets his ♠K. You will lose another diamond trick. Contract made by losing 1 ♠ , 1 ♣  and 1 ♦ . Should had East win the first ♣  trick with the ♣K over the ♣Q, at least you tried your best play and now you still have the finesse of ♠Q to try.

Cross Ruff

You probably took the ♥A and did a complete crossruff so that every trump is made separately. So, you can make 12 tricks (9♠,1♥ and 2♦) but at which stage did you cash your ♦AK? That is the main point of this hand. Say you take the first ♥, ruff a ♥ and come back to your hand 3 times with ♣ ruffs to trump the 3♥ in dummy. If you were in a slam contract, you will go down!

West has one more trump that you have. He will ruff the second diamond and play a ♥ . Now you are cooked because the trump control has passed to the defenders who had opportunities to discard their short suits and can now ruff Aces and Kings. So, the lesson is to cash your winners in side suits before beginning a crossruff.

Since declarer won the first trick with ♠J and you have 14 HCP you know that you will get 4 tricks but then what?  The only possibility of defeating the contract is if partner, West, has the ♦J.  It is the only honor that can possibly be held by West.  Based on that information, at Trick 3 after winning the spade trick, you play the ♦Q.  When this card is played the contract will go down 1.  If partner does not even have that card then you could not defeat the contract.

Stripping Suits

Did you ruff with the ♠A?  If not, then your contract may go down 1!  By ruffing with the ♠A,  you intentionally concede a trump trick, however you eliminate the guess as to who has the ♦Q. So, you ruffed with the ♠A and led a club to the ♣A and ruffed the J♣ .  Now you lead a trump to the ♠K and no matter who has the lead or what is returned you make your contract without having to guess who has the ♦Q.

Unless you are 100% right in guessing the Queen in those situations, by ruffing the third trick with the ♠A, allowed you to bring home the contract.

Rule of 7

Counting your tricks, you have 7 winners and 2 certainties in diamonds. You can afford to lose a diamond but not 4 hearts in addition. So, using the "Rule of 7"  you should duck twice (7-5) You win the 3^rd trick and run the ♦9.  When it loses to the ♦Q, East does not have a heart to return, or if East does then the hearts were split 4-4. So, you contract was made losing 1 diamond and 3 heart tricks.

Note: The Rule of 7 assumes play in a 3NT contract and is as follows: Subtract from seven the total number of cards that declarer and dummy hold in the defenders' suit and duck their lead of the suit that many times.

Defence: Rule of 11 

East knew by applying the Rule of 11 to his partner’s opening lead that South has only one card higher.  Since declarer has already won with the ♠Q, one more lead of spades and it would establish partner’s suit.  It has to be done before clubs are established and West still had an entry.  If declarer had the ♣AQ, there was little hope for the defence.  So, East decided to play his partner for the ♣A. So, play the ♣K and return the ♠J. It turned out, it was the right play.

Loser on Loser

We have potentially 3 diamond losers! So, win ♠K with ♠ A. Play ♣A and ♣K. Play the ♥Q and ♥AK discarding ♦2. Now you play the ♠J and discard ♦8; discarding a loser on a loser. When West is on lead you get a ruff and a sluff or a ♦ into your ♦AQ. Slam has been made no sweat.

Plan at Trick One

Did you ruff the 3^rd round of ♦  with the ♠A or ♠J?  If you ruffed with ♠J you went down 1!  Say you ruff the 3^rd round of diamonds with the ♠J it will be overruffed with the ♠Q and West will return a trump.  So, you will lose one spade, two diamonds, and cannot escape losing one heart for down 1.

Instead if you ruff with ♠A, play the ♥A, ruff a heart and come back to your hand with ♣A.  Then ruff another heart with ♠K. OK you gave up in catching the ♠Q but your contract is safely in. You lost two diamonds and the ♠Q.  It is important to make a plan at Trick ONE.

Plan at Trick 1

If you count you winners you have 3 spades, 2 hearts and potential 3 diamonds and 1 club.  But you need to lose the lead twice because of the missing Aces.

You have to let the ♥10 win.  When East returns a ♥3 you play the ♥J covered by ♥K and ♥A.  You play on the diamonds until the Ace if played.  East cannot return a ♥ so he will have to break another suit which gives you the time to remove the ♣A.

If you win at Trick 1 and start playing on diamonds East will be able to return a heart which you will win but you still have to lose to the ♣A with West and 3 more heart tricks for down 1!

You ruff the last diamond.  If you lead dummy’s last trump next it would be a fatal move. When West took his ♠Q, he would be able to lock you in the dummy. If you tried to reach your hand with a club ruff, to draw the last trump, West would overruff the ♠6 with the ♠9. If instead you ruffed high, his ♠9 would be promoted.

So, you need to cash the cards in dummy that would allow West to lock you there. You play the ♥AK and ♣A before leading the last trump. Now all is easy. When you give West his trump trick, you will be able to ruff or win any return in the South hand and draw the last trump.

The contract has been brought home with a little planning and thinking ahead.

There are no guarantees that this contract can be made however we will try to put the best probabilities on our side.  We can see from both N-S hands that the slam can be made if we can guess which opponent to do the ♥  finesse.  How do we do that?

This involve doing a discovery of how the cards are distributed in the opponent’s hand.  It only involves counting to 13!  Yes, that is it.

So, South wins the club lead and starts drawing trumps to find out that East had 3 spades.  Then the  ♦A, ♦K and ♦Q were led and we found out that and East had 2 diamonds.  So far West had 1 spade and 5 diamonds and East 3 spades and 2 diamonds.  Now a ♣ is lead to find out more information.  After West plays the ♣J his partner overtakes with the ♣K to avoid West to be forced to lead a heart or giving a ruff and a sluff.  East then plays the ♣10 and South ruffs and West discards a diamond.  This last trick was very revealing since it showed us that East started with 3 spades, 2 diamonds and 6 clubs leaving only 2 heart cards.  West started with 1 spade, 5 diamonds and 2 clubs.  That leaves East with 5 hearts and West with 2 hearts.  So, the chances of finding West with the Q is 5 to 2.  As I said there are no guarantees but you did your discovery and you get rewarded by making the slam.

Deception by Defenders

If a defender tries to fool declarer by false carding, the effort may end up fooling also his partner!  However, there are times where a defender can afford to deliberately deceive his partner because he knows that no harm and perhaps some good, can come from his deception.

So as declarer you are thinking since East has overtaken his partner’s K, it must be because he has a doubleton.  Right?  So naturally West also thought that East had started with a doubleton therefore returns the ♥10 for West to ruff.  Since South (declarer) has lost 2 heart tricks and will lose a club trick, he must prevent the loss of another heart trick therefore plays the ♠Q and West follows with the ♥6.  Of course, East wanted North to ruff high so he can promote his own trump.

Declarer could have made the contract had he ruffed with a low ♠ however, thinking that West was overruffing, elected to ruff high.  When East played a ♥  at trick 3, South (declarer) realized that it was too late to do anything about it and the contract went down 1.

Protecting Entries

Did you play the ♥6 or the ♥A. If you played the ♥6 you have just sunk your contract!  You have 5 top tricks and need 4 more coming from the clubs.  You also need 2 entries to South in order to cash in the club suit. If you played the ♥6, West will prevent you from getting back to your hand with the ♥K.

You win the first trick with ♥A.  Cash the ♣A, a diamond to the Ace allows you to lead the ♣Q.  Whichever suit East returns after winning with the ♣K, you will be able to set up and use a heart entry to the South hand.  So, you will have your original 5 top tricks plus 4 club tricks and the contract is made.

Did you overtake with ♥A and returns the ♦K?  By doing so you are increasing your chances to defeat the contract since you are establishing a potential diamond trick.  You can reason that West raise of the ♥  was based on 3, 4 or maybe 5 hearts.  If it is 4 or 5 hearts then declarer will either ruff the 1^st trick or have a singleton.  If it is 3 hearts, the play of the ♥K marks West for the ♥Q too.  So, by overtaking and playing the ♦K is not giving anything away in hearts.

It you do not overtake the ♥K and partner continues the hearts declarer will ruff and will force the ♣A out while keeping the diamond suit guarded with his Ace.  Declarer will get rid of a diamond loser on his spade and will make his 5♣X contract.

Start counting your winners: 2 spades, 2 hearts, 3 diamonds and 3 clubs.  Which suit would be most likely to generate 2 additional tricks with wicked distribution.  You have 8 clubs and 7 diamonds and you have the 10 in both suits.  So, after winning the ♥Q with the ♥K, you lead a low club to the ♣10.  If West plays a ♣ no problem if the ♣10 lose to East which means that there are only 3 outstanding clubs therefore the suit will run.  If West discards and the ♣10 loses to East then there is a marked finesse against the ♣9.  You enter dummy and finesse against the ♣9 and again you will have 12 tricks and bring home your contract.

You need to unblock Dummy.

Did you win the trick with the ♠A? If not, you will go down 1.  Counting your winners, you have two spades, four hearts and three clubs will give you a total of nine. What is the best play in the heart suit? You should lead low to the ♥J, return to a club and lead your remaining low heart. When West began with a doubleton ♥K, as here, it will appear on the second round and you will win with dummy’s ♥A. Dummy then has the ♥ 102 opposite your bare ♥Q. The suit is blocked.

That is exactly what will happen if you win the first trick with the ♠J. Dummy will have no spade entry to enable you to untangle the blockage in hearts. If you return to the ♥Q and lead the ♠4 towards dummy’s ♠Q, West will go in with the ♠K to prevent you from reaching the dummy. One down.

The solution is to win the first trick with an apparently unnecessary high card, the ♠A. You then play the hearts as suggested above, ending with the ♥ 102 opposite your ♥Q. No matter! You return to the ♥Q and lead a spade towards the ♠Q. West cannot stop you from reaching the ♥10. Nine well deserved tricks are yours.

South must duck the first diamond to remain in control.  If a diamond is continued South wins with the Ace and ruffs a diamond in dummy.  If instead East switches to a trump at trick 2, South drives the ♠A and draws trump as soon as he gains the lead and then discards all his losers on the established hearts suit.

The danger in winning the first diamond and then leading a trump next, is the defence can immediately score 2 diamonds tricks and 2 Aces for down one.  If South leads a diamond instead and hoping to ruff a diamond in dummy, the defenders will cash the ♠A before collecting another diamond and the ♣A.  If South tries to cash 3 hearts in order to discard a diamond, West will ruff the 3^rd heart for down one.

It is most important to develop a plan at trick one and not play quickly.

Protecting Entries

Did you play the ♦6 or the ♦K. If you played the ♦6 you have just sunk your contract!  When East produces the ♦Q, you will have to play the Ace and not have any more entry to South’s hand.  You will lose the South’s spade winners. (West will hold up the ♠A for one round.). If instead you allow the ♦Q to win, East will return a diamond with similar effect.

If at Trick 1, you made a plan and had played the ♦K and start playing on the spades suit you would have made your contract easily.  You can count five winners outside the spade suit and add four spade tricks for a total of 9 tricks. To guarantee four tricks from the spade suit, you must win the first trick with the ♦K. You then lead the ♠J and continue the suit. With your most important ♦A entry intact, you cannot be deprived of at least nine tricks.

Did you play low from dummy at Trick 1?  If you did your contract probably went down, when it was cold.  If you did so, East won with the ♦ K and made a bright switch to the ♥ 5. Declarer finessed the ♥ Q, losing to the king, and back came another heart to remove his ace.

If you made a plan at Trick 1, then you may have been more successful.  You should rise with the dummy’s ♦ A at trick one, giving East no chance to find a possibly damaging heart switch. Declarer can then run the ♣J into the safe (West) hand, not caring whether the finesse wins or loses. When West wins with the ♣K and returns another diamond, East wins with the ♦ K and declarer makes an overtrick.

West is likely to hold the ♦A after his overcall. If he began with ♦A-x, he will have to play the ace on the second round and your ♦K will live to score a trick. However, there is a better way to play the contract.

If West holds the six spades, you can endplay him. Since you will have to lose a round of spades and would not like East to win this (and switch to a diamond), you should allow West’s ♠K to take the first trick. You win the spade continuation with dummy’s ace and draw trumps in three rounds. You then play three rounds of clubs, ending in the dummy.

When you lead the ♠6, East discards his club. You then throw the ♦5 (a loser-on-loser play). West has to win the trick and has to return a ♦ or a ♠. A diamond will allow you to make the ♦K and a spade will give you a ruff-and-sluff.

Without your duck on the first trick, you would have gone down. East would have won the second round of spades and switched to the ♦J. This is also called an avoidance play.

If you lead a club to the jack, or play the ace and jack of clubs, East will win and return a second round of trumps. Dummy is then a dead duck. You will lose two hearts and two clubs, going one down.

You must find the unusual play of leading the ♣Q from your hand. If one of the defenders wins with the ♣K, you will cross to the ♣J for a discard on the ♦A. It will not help them to duck the ♣Q. You would then reach dummy by playing the ♣A and ruffing a club.

When you have no obvious entry to one hand, sometimes you need to be creative.  This was one such example.

Killing the Dummy

Trick 1: Partner leads ♥J and declarer wins with the ♥Q.  Declarer plays a small ♣ to the ♣K.  Then declarer plays the ♣Q.

East needs to know if his partner has started with 2 or 3 clubs.

If West has played high-low (meaning holding 2 clubs), East must hold up his Ace once more because it means that South (declarer) has started with 3 clubs.  However, if West has played a small club showing 3 clubs (low-high) then East has to take the second trick and dummy is no longer accessible.

Here we always assume most probable distribution however if declarer has started with 4 clubs and West had a singleton then declarer will always access his dummy.

It is most important in these cases to give count to your partner so that partner knows when to take their Ace. If the Ace is taken too soon you allowed the opponents to make their contract.  If the Ace is taken too late, you allowed the opponents an extra trick.

Did you pitch a ♠ at trick one?  Need to prevent the dangerous hand to be on lead.

If you pitch a ♠ at trick one, you cannot be defeated.  Independently how West continues.  You will make your contract and maybe an extra trick!

Let’s assume that West continues with the ♣A, you will ruff, play a ♠ to the ♠A and ruff a ♠ high, enter dummy with a trump and ruff another ♠ high, thus establishing 3 spade tricks in dummy.

After you next cross to dummy with a trump, you discard the ♥KJ4 on the ♠J107 and wind up making the contract with an overtrick.  Of course, you do not make the overtrick if West cashes the ♥A at trick 2 however you still make your contract.

You needed to break the communications between East and West to prevent the dangerous hand to be on lead.

You should unblock the ♣A and overtake the ♥J with the ♥A. This sets up a trump trick for West, it’s true. In exchange, you have an entry to the South hand and will reel off your sequence of club honours. West can enjoy his trump trick when he wishes. Dummy’s three top spades will bring your total to twelve.

West lead the ♦A and East wanted the suit continued so he played ♦10.  By doing so West knew that South had the ♦J otherwise East would have played the bigger of the two touching honours to show to continue the suit.  So, since East did not play ♦J, then South must have that card.

With the ♦Q in dummy there was no point to continue the diamonds to partner’s ♦K because it would establish the ♦Q for a discard in spades. So, it was mandatory to switch to spades rather than to continue the diamonds.

So, West switched to ♠J where East played the ♠2 and declarer plays the ♠4.  Now West knows that his partner has ♠KQ otherwise declarer would have played one of them.

As a result, of properly signalling and interpreting the cards South eventually lost 2 spades and 2 diamonds to go down one.  Failure to read the cards properly would have allowed N-S to make their contract easily.

The Backward (or Chinese) Finesse

Counting your tricks, you get 2 spades, 2 hearts, 1 diamond and you must manage 4 tricks in clubs.  So, what is the best line of play keeping West off lead because it is the dangerous hand and has probably 2 more diamonds to cash.  If you have to lose a club trick then it is best to lose it to East.  So, you lead the ♣J if West covers you take your ♣A and if not, you let it ride to East.  If East wins it and has a diamond no problem because it means that diamonds were 4-4 and your contract is guaranteed.  When East wins and plays another suit, you win in dummy and play another club.  The contract is in since the clubs are 3-2.

The Scissors Coup

You count your losers and you have 2 heart losers and 1 diamond loser.  However, you may suspect that the ♠J is a singleton so you need to ensure that you do not let East be on lead.  Accordingly, you play you last ♣ and pitch your last ♦ .  You are preparing for the next few moves.

If East ruffs you overruff, and if West wins then he cannot reach East with a ♦  to get a spade ruff.  You can proceed to play trump and surely you will lose 2 hearts and a club trick but the contract is made.

If you had not played your last club to pitch your last diamond, and instead played trump East would have duck to West ♥K and return a diamond to East’s Ace who would have given West a spade ruff.  So, you would have lost 2 hearts, 1 diamond and 1 ruff for down one.

So, you severe the communication between the defenders which is also known as the Scissors Coup.

This is swapping losers.

It is a reasonable contract but can you see the potential problem? You could lose a ♦and some hearts. You do not want East on lead and switch to hearts.  So, you need to prevent East to be on lead.

So, you duck the ♣K and if ♣ is continued you take it discarding a ♦  from dummy or if West switch to something else no problem.  You will then play 2 rounds of trump with ♠AJ and the ♣A discarding a ♦ .  You then play ♦AK and ruff high the third ♦ .  When the suit breaks 3-2 and the trumps are no worse than 3-1 your contract is home.  You enter dummy with ♠Q and cash in the ♦s discarding the losing ♥ .

You had a losing ♦  from the start.  You chose to lose a ♣ instead to make sure that the dangerous hand did not gain the lead.

This is Safety Play.

Only 4 club tricks are needed to make this contract and it is perfectly clear that South does not have any side entry.  What, then, is the danger?  That the clubs will break 4-1 or worst 5-0 which happens 1/3 of the time.  I know we always operate under the assumption that suit will break as they break most of the time.  However, I cautioned you that you must make your contract and that it is an IMP game where extra trick are irrelevant.

So, you enter dummy and play a club and finesse the ♣10.  If it wins you will make 11 tricks but if it loses, you are guaranteed 10 tricks.

So, this safety play will cost one trick part of the time but the contract is always guaranteed and any unfavorable distribution.

How many tricks did you get?  13. You should since the contract was 7♠.

Did you do a Dummy Reversal?

The proper line of play does not rely on finding the trumps divided 2-2 or the hearts divided 3-3 or 4-2.  After winning the lead, ruff a ♣with the J♠, lead the 4♠ to the 7♠, ruff a ♣with the K♠, lead the 10♠ to the Q♠ and ruff the 9♣ with your last trump A♠.  So far you have 4♣ and 2♠ for 6 tricks.

Now lead a ♦  to the K♦  draw West’s last trump with the 9♠, and you cash K♣  and 8♠, a ♦  to the A♦  and AK♥  for another 7 tricks. Voila 13 tricks.

Did you pitch a ♥  at trick one?

If you did not pitch a ♥  at trick one, you will lose 2 heart tricks.  For sure you will lose the lead to the ♣A but your ♣K will be established to pitch a losing ♥  on it.

Try any other ways and you will see that you cannot make the contract without the ♥  pitch.

Did you play the ♠Q?

The one vital piece of information East has is that he has a sure entry and that West probably does not have.  The ♦K will make a sure entry.  It is possible that West may have the ♠K but giving that South bid 3NT the odds are against it.  Declarer does not have much in ♣ and it is unlikely to bid 3NT with two unguarded suits. Even if West has ♠K, it will not matter if East plays the ♠Q or ♠A.

If East plays the ♠A at trick one and plays the ♠Q at trick two, declarer will duck and the third spade clears the suit but there is no longer a link between the two hands (E-W).

Further by playing the ♠Q at trick one, declarer would not dare ducking it, since he expects West to have the ♠A.

It was vital to play the ♠Q rather than ♠A to maintain communications.

You know that East has the ♠10.  He must have a higher spade because West would have led the king if he had the ♠KQJ.  If East had the ♠K10x, he would have played the king at trick one.  You have another way of knowing that East does not have the ♠K10x.  If East had started with the ♠K10x, then West would have started with the ♠QJxxx, and he would have led the queen from that holding.

If East had the ♠Q10x, he would have played the queen at trick one.

If East had the ♠J10x, he would have played the ♠10 at trick one.  But that means that West would have started with ♠KQxxx and he would have led the king from that holding, so East does not have the ♠J10x.

The ♠7 is fourth best.  East has three spades higher than the 7.  And, we know from the bidding that West has five spades and East has exactly three spades.  East does not have a fourth spade.

If you think about it, the only holding East can have is the ♠QJ10.  The bidding marks him with three spades so West has all the rest.  It is the only layout consistent with East’s play of the ♠10 and West’s lead of the ♠7. 

Knowing about the spade honours can be useful if you have to make guesses about honours in other suits.  Reflecting on the bidding you know that East has 6 to 9 points.  You have learned that he has the ♠QJ10 after seeing the ♠10.

Did you take the trick and lead another ♥ ?

You are not going to take a trick in clubs and even if partner has the ♦K it would be finessable (assuming declarer can get to dummy).  However, you have no need to rely on some fortunate distribution of the outstanding cards since the way to defeat the contract lies in your own hands. Partner is marked with the ♥Q, and by simply overtaking the king with the ace and returning the suit you will force declarer to ruff in dummy, thereby ensuring a trick for your ♠10.

Did you think about a Dummy Reversal?

First did you notice the spots on the cards?  You want to make sure you do not get overruff.  Usually you ruff with the “short” hand but this time we will ruff with the “long trump” hand.  Hence dummy reversal.  Declarer becomes the dummy.

You win the ♠K and ruff a ♠, play a ♣ to Q, 2^nd ♠ ruff, ♣ to the A, 3^rd ♠ ruff.  So far, we have 6 tricks.

Then a ♦  to A and 4^th ♠ ruff (high) ensuring we leave a small ♥  to return to dummy pull trump and finish with a small ♣ to the KJ.  This is an additional 7 tricks for a total of 13 tricks.

Voila!  Brought the contract home.  May need a new partner bidding a grand Slam on 28 HCP!  But your play was perfect.  Remember fits takes tricks not just HCP.

PS: We always assume regular distribution of cards not adverse.

Did you kill the dummy?

Count the Diamond cards between declarer, dummy and defender.  12 diamonds accounted for therefore declarer has only 2 Diamond cards.

In order to make sure that declarer does not cash all his ♦  you must ensure that there are no entries left to the dummy.  Therefore, you must immolate your ♠K by playing it at trick 3.  Do not play a low because if declarer has the ♠Q he will win the trick and then play his last ♦  and re-enter the dummy with another ♠ and cash the remainder of the ♦ .

The ♠A has been played by East on the first trick.

The ♠K is held by West.  If East had the ♠A and ♠K, he would win the first trick with the king, not the ace.  This is standard technique for defenders.  When you play third hand to a trick, and if you hold an honor sequence (AK, KQ, QJ), you play the lowest card in the sequence.

For example: holding KQ72, it is correct to play the queen.  Holding QJ1072, it is correct to play the 10.  If with AK72 you take the first trick with the A, partner will not know that you have the king.  Partner may think that declarer has the king.

So West has the ♠K because East’s play of the ace denies having the king.  This is a very strong clue since a defender wants more than anything to have an informed partner.  Partner is your friend so you do not try to confuse partner.

Who has the ♠Q?  As previously mentioned since West is holding the ♠K, if he would also hold the Q, he would have led the K from a sequence of KQ.  Therefore West does not have the Q, East has the queen.

Who has the ♠5?  West has/had it since he lead it.

Finally who has the ♠2?  You will notice the spots you started with in your hand and dummy.  Also if you remember the bidding you know that West has 5 spades. West led the 5, which is the fourth best.  That also means that there are three spades higher than the 5 and one spade lower than the 5.  Your dummy has the 4 and you hand has the 3♦.  The only spade that West can have lower than the 5 is the 2.

West has something like KJ952 and East has something like AQ107.  West cannot have six spades for two reasons.  The first is that the spot cards tell you that West has exactly five cards.  The second reason is that is West has six spades, he would have bid over 3♦.  This is human nature, almost as strong a clue as there can be.

Believe it or not, there is another important point you can learn from what you see at trick one.  East raised 1♠ to 2♠ with AQ107 (or so).  Then he passed when you bid 3♦ .  East did not bid 3♠.  He must have a really bad hand.  Almost certainly he has something like:

♠AQ107  ♥xxx   ♦xxx   ♣xxx

If East had a doubleton or if he had any extra values such as a jack or a queen, he might have bid 3♠.

Make sure you use that information when you play the hand.