Morton's fork coup

Morton's Fork is a coup in contract bridge that forces an opponent to choose between:

1. letting declarer establish extra tricks in the suit led; or
2. losing the opportunity to win any trick in the suit led.

It takes its name from the expression Morton's Fork.

Example

It appears that South has both a heart and a club loser. Although South can establish another winner in diamonds, just one discard on a diamond honor doesn't help.

South in 6♠		♠	K Q 9 8
		♥	K 9 8
		♦	K Q 9
		♣	K 9 8
♠	3	N W               E S		♠	2
♥	A 10 5 3			♥	J 6 4 2
♦	J 10 7 3 2			♦	A 8 6 5 4
♣	J 5 4			♣	Q 3 2
Lead: ♦J		♠	A J 10 7 6 5 4
		♥	Q 7
		♦	-
		♣	A 10 7 6

South receives the lead of the ♦J against 6♠. However, there are two ways that the contract can be made. South might manage to avoid any heart loser. Or, South might take two heart tricks; in that case, South could discard one club on the ♥K and another club on a diamond honor.

Judging from the opening lead that East holds the ♦A, South plays the ♦9 from dummy at the first trick, ruffs in hand, and draws trumps. Hoping that West holds the ♥A, South leads the ♥7, executing Morton's Fork:

If West takes the ♥A, declarer can win any return, unblock hearts, take a ruffing finesse against the ace of diamonds, then discard two clubs on dummy's winning diamond and ♥K. In this case South loses only a heart. If West ducks South's lead of the ♥7, declarer wins dummy's ♥K, takes a ruffing finesse against the ace of diamonds, and throws the ♥Q on the established diamond winner. In this case South loses only a club.

Note that declarer must be careful not to play a high diamond on the opening lead, as East could then withhold the ace. That would force the declarer to choose a discard prematurely. South must get a discard on a diamond honor eventually, but not before West has been forced to decide whether to take the ♥A or duck it. Only then will South know whether to discard a heart or a club on the diamond winner.

Example Defense

South in 6♣		♠	K 2
		♥	-
		♦	10 7 5 4
		♣	K Q J 10 6 5 4
♠	A J 7 6	N W               E S		♠	10 5 4 3
♥	A K J 2			♥	7 6 5 4 3
♦	J 9			♦	Q 6 3 2
♣	7 3 2			♣	-
Lead: ♣2		♠	Q 9 8
		♥	Q 10 9 8
		♦	A K 8
		♣	A 9 8

Robert Gray gives this spectacular example of an impossible defense to Morton's Fork. West leads the ♣2 against South's six club contract. South wins and initiates the coup by leading the ♠8.

If West takes the ♠A, he might as well continue with the ♣3. South wins and leads a heart, covered and ruffed. A third club to South's hand, and another heart, again covered and ruffed. A diamond to South's hand, and a third heart covered and ruffed. The ♠K is cashed, and then another diamond to South's hand allows dummy's last two losing diamonds to be discarded on the ♠Q and the established heart.

If West ducks the ♠A at the second trick, South sets up a heart via ruffing finesses as before, discarding dummy's losing spade on the established heart. Now a third diamond from South either wins or establishes dummy's ♦10, and South has twelve tricks: one spade, one heart, three diamonds and seven clubs.

Gray points out that to defeat the contract, West must lead the ♥2 at trick one. (He goes on, "And I hope that is not too obvious.") Against the opening lead of the ♥2, South must discard from dummy before West has been forced to play to South's spade lead. If South discards dummy's spade at trick one, West's ♠A will later take dummy's ♠K, and South must lose a spade and a diamond. If South discards a diamond from dummy, West ducks South's spade lead, saving his ♠A for the ♠Q, and again South must lose a spade and a diamond.

Gray speculates on a name for West's opening lead coup: "This play of giving declarer a trick early . . . is probably worth a name. The Anti-Morton Coup or the Down With Morton Coup spring to mind, but these names seem rather unfriendly. Let us settle for the Morton Coup Defense."

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