Deal 17
 
  6
OL: ♠K
♠ 10 7 2
J 8 7 3 2
A K Q
♣ A K
 
 WEST  NORTH  EAST  SOUTH
1
pass3pass3NT
pass6passpass
pass

You are East. The bidding has been as shown.

West led the ♠K, won by South's ♠A.
South played a small ♣ to dummy's ♣A, then led dummy's J.

What do you play? Q or 4?

When you have made your choice click NEXT .
♠ K


♠ 8 4 3
Q 10 4
8 7 3
♣ J 8 7 4
  ♠ A


♣ 2
 

 
Deal 17
 
  6
OL: ♠K
♠ 10 7 2
J 8 7 3 2
A K Q
♣ A K
  Play the 4.

Remember that South opened 1, so he has 5 of them.
With only 3 trumps out he has no intention of finessing. Perhaps he led the J just to tempt you to cover in this situation.

If you play low he will win with one of his high s and then you will have a sure winner. Along with the ♠ winner West has you will defeat the slam.

If you cover the J with your Q South will again win with one of his high ones.
But now the position will be clear to South and he will return to dummy and play another , finessing your 10. With no trump loser he will make the slam.

 Deal 18 
♠ K Q J 9 5
--
9 6 4 2
♣ 9 6 5 3
♠ 8 4 3
Q 10 4
8 7 3
♣ J 8 7 4
  ♠ A 6
A K 9 6 5
J 10 5
♣ Q 10 2