The abnormal is abnormally tough

William James, the first person to teach a psychology course in the United States, said, “To study the abnormal is the best way of understanding the normal.”

Maybe that applies to bridge. Most deals follow a well-known path, but occasionally one that is abnormal appears. In this deal, South is in four spades. West leads the diamond six, and declarer wins with dummy’s ace. What happens after that?

South’s two-spade rebid promises at least a six-card suit (and in Standard, a minimum opening). If playing two-over-one, North might continue with two no-trump, over which South should bid three clubs. That would steer North away from three no-trump (which would not do well if East were to lead a diamond).

South has four potential losers: one spade, two hearts and one diamond. However, if he can draw trumps, he can run the clubs to take at least 10 tricks.

After winning the first trick, declarer will run the spade queen. West is in, but what does he do next?

West must be guided by his partner’s signal at trick one. Here, East should see the advantage of a heart shift. So, East should signal with a discouraging diamond two. Then West ought to find the heart switch.

If East plays an encouraging diamond 10, West might cash his diamond queen at trick three. If so, East should drop the two, his lowest from a remaining odd number of diamonds. Then West might shift to a heart; but he is more likely to continue diamonds, influenced by that trick-one signal.