Defense at Trick One

Last night in the team game I declared a hand where the defense allowed a contract to be made at both tables that might have been set. You hold:

S A75
H J4
D 974
C Q6542

Both sides are vulnerable. The bidding:

LHO Ptr RHO You

2C 2D P* P
2H P 2NT P
4H P P P

* showing some values

Partner leads the Jack of spades. Dummy has:

.................S 9432
................H 92
................D K532
................C J87

S A75
H J4
D 974
C Q6542

How do you defend?

Consider what declarer has, given this bidding and the opening lead. Partner put in a vulnerable 2D overcall, so is likely to have all of the missing diamonds, so declarer is void. His lead of the Jack of Spades probably means he has the ten also, but the bidding surely indicates that declarer has the KQ.

So how can the defense get 4 tricks? The only chance is 2 Spade tricks and 2 Club tricks. But in order for the defense to have a chance, it is necessary that you duck the spade Ace. Declarer has no entries to dummy, so he cannot play a spade through your Ace later on. But if you put up the Ace, he will score his KQ easily. You have to make declarer play both clubs and spades from his hand.

This is the full hand:

9432
92
K532
J87

JT6..............A75
53.................J4
AQJT86.......974
KT................Q6542

KQ8
AKQT876
-
A93

Playing the ace gives declarer 10 easy tricks. Ducking gives the defense a chance. Declarer might still make it if he guesses right and manages an endplay, but it isn't easy and he might go wrong.