Trump Coup - Grand Coup

If the card which is ruffed in order to shorten the trumps would have been a winner, the play is called a grand coup:

South, having opened strong 2♣, plays in 6♣. West leads a diamond to East's ace, who returns a heart to South's ace. South plays A-K of trumps and discovers the bad break.

Now, South has to ruff his high spades in dummy twice to shorten its trumps to the same length as West; he cashes two high spades, discarding a heart from dummy, and ruffs the spade queen. Next, he enters his hand with the ♦Q and ruffs another spade. He cashes the ♦K, and reenters his hand with the ♥K. At that point, North and West have only two trumps each—K 10 and J 9 respectively. Either a heart or a spade from South's hand completes the coup.

Often, for a trump coup to work, the key defender must have a suitable distribution in other suits, so that he cannot ruff a declarer's winner prematurely.