Cover the East-West thumbs and plan the play of the slam against the lead or the queen of hearts.

If you were not careful at tricks one and two, you probably lost the slam. Observe what may happen if South plays carelessly to the first two tricks.

Dealer North, none Vul

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

The Auction:

West North East South
1 Pass 1
Pass 2 Pass 3
Pass 4 Pass 6
Pass Pass Pass

Delcarer wins the first heart in dummy to lead the 10 for a first round finesse against East’s queen. (This play is better than first playing a high spade to cater to a singleton queen offside).

The 10 holds the trick and South continues spades and picks up East’s queen.

South next goes after the diamond suit with the intention of establishing the suit and discarding the losing club on the long diamond. Howewver, East foils this plan by refusing to play the A on the first two leads, and declarer is forced into a losing club finesse for down one.

The winning line of play: Declarer won the opening heart lead in his hand and inmediately played diamonds. East was helpless. If he took the A South would have more than enough entries to make the spade finesse and to run the diamonds.

East ducked his A and South countered by using this entry for the spade finesse. The 10 was passed successfully, the finesse was repeated, and trumps were drawn.

Diamonds were established, East ducking until the third round. However, the K was still in dummy to provide entry to the fourth diamond.

By ferlema