Source: IBPA Column Service Jun 2018
Dealer North. E/W Vul
A 10 9
A Q 10 8 7 6 2
|10 6 3
8 7 4 3
J 8 7 5 2
|K Q J 9 5
K J 4
Q 10 4 3
|8 7 4 2
K Q J 5 2
After South had bid two hearts, North asked for key cards with four no trump. When South admitted to two key cards plus the queen of hearts, North made a grand slam try by bidding five no trump, guaranteeing all the key cards and the queen of trumps. He was hoping that his partner would show him the king of diamonds.
When South denied holding that card by bidding six hearts, North gave up on the grand slam. As North had made a grand slam try, West saw that it was pointless to lead his singleton diamond: it might well guide declarer into a winning line. So, West led a third-highest three of spades.
After winning the first trick with the ace of spades, declarer cashed the ace of trumps to make sure that trumps were not 5-0. When both opponents followed, declarer decided to try to set up dummy’s long suit, the diamonds. Rather than risk a finesse in the suit, declarer played the ace and another diamond.
After winning with the jack of diamonds, East forced dummy by playing a high spade. Declarer ruffed this with the nine of trumps, then drew a second round of trumps with dummy’s ten. Next, he ruffed a diamond high, thereby establishing the suit. All that remained for declarer was to draw West’s two remaining trumps and claim twelve tricks: one spade, a spade ruff, five trumps, two clubs and three diamonds.
Of course, if trumps had been 5-0 declarer would have needed to manage the diamonds for one loser without being forced to ruff a diamond in hand.