Deal 3
 
  3NT
♠ K 9 8
A 8 5
Q J 9 4
♣ 9 7 3
 
 WEST  NORTH  EAST  SOUTH
1NT
pass3NTpasspass
pass

The bidding has been as shown.
Partner led the ♣4, dummy played the ♣3 and it is your play.

When you have made your choice click NEXT .



♣ 4
♠ Q 7 4 2
9 7 4 3
8 7
♣ Q J 2
 


 

 
Deal 3
 
  3NT
♠ K 9 8
A 8 5
Q J 9 4
♣ 9 7 3
  Third-hand-high is usually a good plan to follow, certainly that is true in this deal.
But that doesn't mean you should blindly play your HIGHEST card, rather you should play the LOWEST of high-equals.

In other words, in this case you should play the ♣J, which is equal to the ♣Q.

If instead you play the ♣Q, figuring it makes no difference, you'd be right that it makes no difference to you. But partner would then assume that it is declarer with the ♣J, and when he obtains the lead with the K he will be unlikely to lead another ♣, which would be too bad for your side.

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