Contract Bridge

Assume you’re West, defending against three notrump. You start by leading the K-Q10 of hearts, declarer winning the third round with the ace. Your partner played high-low to the first two tricks and followed to the third, so apparently he also started with four hearts.

South now leads the A-Q of clubs, and you properly take the queen with the king. This is because there’s no holding possible with which you could gain by ducking the queen, but there are some holdings South could have where you could lose by ducking.

East’s jack falls on your king, indicating that declarer has the ten, which is blocking the suit. It is at this point that you should be very careful about what you do next. For example, if you cash your nine of hearts, South will discard his ten of clubs and easily score nine tricks.

But resisting the impulse to cash the heart nine at this juncture is not good enough. Given declarer’s opening two-notrump bid and what you can see in your own hand and dummy, it is a virtual certainty that if South is allowed to score four club tricks, he is sure to make the contract.

And so, in an attempt to cut him off from dummy, you should shift to the king of diamonds! If you make this play, South goes down one; if you don’t, South makes the contract.

While the king of diamonds is admittedly an unusual play, this doesn’t mean that it is impossible to find. On the contrary, you have all the information needed to justify it. It is true that declarer might have a hand where he can make the contract no matter what you do. But it is also true that the king of diamonds is the only play that gives you a chance to defeat the contract when it can be defeated.