Grosvenor Gambit - Example

Example

The following deal provides an opportunity for a Grosvenor coup by West:

Against South's 3NT West leads ♥A and continues with ♥K and two more winning hearts. South wins the spade continuation, and has to run the diamonds without losing any further tricks. He therefore plans to play the ♦A and next to unblock by playing the ♦J to the ♦K, hoping for a 2-2 split or a singleton ♦Q (this is the percentage play with the given holding). On the actual layout, South cannot succeed. See, however, what happens when West drops the ♦10 under the ♦A. Declarer now has the opportunity to make his contract by next letting the ♦J run. This play, however, is utterly illogical: it can gain only when West has started with Q-10-6, but with that holding West would "never" play the 10 first. So, South plays for a 2-2 holding in diamonds and on the second diamond trick overtakes the ♦J with the ♦K, only to see East show out.

South will regret not having finessed, and - per Grosvenor's theory - will be furious with himself for not taking the illogical play, for not guessing that West would misplay from ♦Q 10 6. Worse yet, North may blame declarer for not having made the impossible play of letting the ♦J ride. East-West are expected to reap even more benefit on the following boards, due to the emotional storm that West has stirred up for North-South.

In his 1973 article, Turner describes various other examples, including one in which a Grosvenor gambit is successfully deployed by declarer.