Deal 19
 
  6
OL: 3
♠ 6
Q J 9 6
Q 6 3
♣ A 7 4 3 2
 
 WEST  NORTH  EAST  SOUTH
1
pass3pass4NT
pass5pass6
passpasspass

You are East. The bidding has been as shown.

Partner led the 3, you play 10 and South wins the A.
South pulls the last two trumps by leading low to dummy's Q.
He now calls for the ♠6. Will you play your ♠A or not?

When you have made your choice click NEXT .

7 3

♠ A 10 8 7 3
10 4
K J 8 4
♣ 9 8
 
A 2

 

 
Deal 19
 
  6
OL: 3
♠ 6
Q J 9 6
Q 6 3
♣ A 7 4 3 2
  Play the ♠3.

When a singleton in dummy is led through your Ace it is more often better to play low than to go up with the Ace. Declarer might not even have the King, or he may have the King Jack combination and guess wrong.

Here it works out best to play low even though South has the ♠ K Q 5.

Assume you play your ♠A. South will play his loser, of course, and later will be able to discard two of dummy's s on the ♠ K Q. He can then ruff his two losers and make the contract.

Now assume you play low. South will play the ♠Q which will win the trick and he will no longer have a ♠ loser.
BUT - now he will have no way to dispose of the two losers and will go down 1.

 Deal 20 
♠ J 9 4 2
7 3
10 7 5
♣ Q 10 6 5
♠ A 10 8 7 3
10 4
K J 8 4
♣ 9 8
  ♠ K Q 5
A K 8 5 2
A 9 2
♣ K J