North opened One Heart, South responded One Spade, and North jumped to Four Clubs - a splinter, showing shortage and agreeing spades. With no diamond control, South bid only four spades and North subsided.
In spite of the heart bid on his left, West chose the "safe" lead of the queen of hearts. Dummy won, and East's nine looked suspiciously like a singleton to declarer.
Clearly the hearts had to be established and, after drawing trumps in three rounds, declarer led the eight of hearts from hand. The plan was neat enough - after West had covered with his 10, dummy would win and lead the seven, on which South would discard a loser.
The defenders would be welcome to their heart trick and two diamonds, but then dummy would be high.
There was a fly in the ointment, however - West did not cover the eight of hearts. Although declarer could make three heart tricks, he could not bring in the whole suit, and ended one off.
South's slip came at trick one. Instead of following with his three of hearts, he must unblock with his eight. Now there is nothing that West can do to upset South's "loser-on-loser" plan.Reuse content