THUNDER BAY DBC
TIP#7GUY COUTANCHE HIGH OR LOW
Low or High?"
Tip: If playing a low card instead of a high one can't hurt, and may help, play the low one.
The "tip" was not mentioned in this recent bridge column from the Chronicle Journal, but deserved consideration.
North-South were presumably playing "Standard", not two-over-one game force.
Dealer: East
Both vulnerable
              North
             ♠ QJ
             ♥ Q10963
             ♦ KQ83
             ♣ J8
   
West               East
♠ 1062            ♠ 9
♥ A4               ♥ J52
♦ Jl06             ♦ A9752
♣ Q10632      ♣ A975
             South
            ♠ AK87543
            ♥ K87
            ♦ 4
            ♣ K4
W      N      E       S
                 Pass  1S
Pass  2H   Pass  2S
Pass  3S    Pass  4S
All Pass
Opening lead:  ♦J
As reported in the column, East covered the diamond king and daringly switched to a low club, putting declarer to a guess. When South played low, he lost two club tricks and went down one.
The "tip" might have helped here. West's diamond lead is surely not from ace-jack, so why not play low from dummy? Ducking the jack can't hurt here, as a club lead from West can't hurt you, and you can always ruff out East's ace later for a club discard. Now East is put to the test: he has to overtake partner's jack if he wants to shift to a club. Not easy! For example, what if the layout was:
            North
           ♠ QJ
           ♥ Q10963
           ♦ KQ83
           ♣ J8
West               East
♠ 1062            ♠ 9
♥ A4               ♥ J52
♦ Jl064            ♦ A9752
♣ K1063          ♣ A975
            South
           ♠ AK87543
           ♥ K87
           ♦ -
           ♣ Q42
Now playing the ace on the jack would be fatal, allowing an unmakeable contract to come home.
A corollary to the "tip": holding this combination of king-queen-small-something in dummy and shortness in hand, it's usually best for declarer in a suit contact to duck if the suit is led, hoping to score two tricks later.
This tip is useful in many situations, whether declaring or defending, and should always be given careful consideration.