Source: Lakeland Ledger – 1 Dic 1997 by The Aces Good defenders use conventional signals to help guide a touchy defense. For example when West leads fourth best at no trump and East wins the first trick, the card he returns helps West decipher they original holdings in the unseen hands.
Ira Corn
Ira Corn
If East started with four or more cards in the suit he conventionally returns his original fourth-best. If he began with three, he returns his higher remaining card. These conventional plays can be very useful, however, they cannot take the place of judgment. Today’s game serves as an example. N/S Vul. Dealer South.
A 8 6 2 K 7 3 9 7 4 3 Q 10
K 10 5 3 Q 10 9 A 5 A 5 4 2 Q 9 4 8 4 2 10 8 6 2 7 6 3
J 7 A J 6 5 K Q J K J 9 8
West North East South
Pass 2 Pass 2
Pass 3NT End
Openning Lead 3 West leads his fourth best spade and East’s queen wins. What happens if East returns a conventional spade nine? South covers, as does West, and after dummy’s ace wins, South has a sure second spade stopper in dummy’s 8 6. With the danger in spades gone, South concedes a club and a diamond, but he has his nine winners. When South drops the spade seven under East’s queen, East must realize he cannot sacrifice his spade nine to convention. He knows that South has only two spades and that one of them is most  likely to be the 10 or the jack. Wisely, East returns the spade four instead of his nine. The difference? After West covers South’s jack and dummy, ace wins, West can return a low spade after he wins his club ace. East s nine wins the trick, and when West wins the ace diamond, he takes the setting trick with his 10 of spades. A nine is a terrible card to waste.