West leads the two of hearts against 3NT. Since the other suits are strongly protected, you hold up the ace of hearts until the third round. Hearts prove to be 4-3, as was indicated by the fourth-best lead of the two. How should you continue?
The original declarer continued blithely with the ace and queen of clubs. When West correctly held up the king of clubs, declarer was left with a maximum of eight top tricks, even if the diamonds split 3-3. He therefore crossed to the ace of diamonds and ran the ten of spades. West won with the spade king and cashed a long heart followed by the king of clubs. One down!
It is one thing to go down in a contract when you have missed a slightly better line that would have worked. It is quite another to go down when you could have made absolutely certain of the contract by playing it the right way! Here declarer needed to lead the queen of clubs at
Trick 4. If West captured with the king, proceeding to cash his long heart, nothing could have prevented declarer from scoring the remaining tricks.
If instead West held up the club king, declarer could switch to spades to set up the two extra tricks that he needed for game. The difference between this line and the one originally chosen is that by retaining the ace of clubs, declarer can avoid losing a club trick when West decides to hold up the club king.