The Vienna coup is an unblocking technique in contract bridge made in preparation for a squeeze play.[1] It is so named because it was originally published by James Clay (1804-1873) after observing it being executed in the days of whist by "the greatest player in Vienna" — identity unknown.[2]
Examples
♠
A J
Example 1 South to lead
♥
A
♦
—
♣
2
N
E
S
♠
K Q
♥
K 4
♦
—
♣
—
♠
4
♥
Q 2
♦
—
♣
A
On the play of the ♣A by South, East is squeezed but can escape by throwing a small heart. Although the ♥Q is now set up, South must next play either the ♥Q, ♥2 or ♠4 to be won in dummy and has no entry back to cash it; he must now lose a spade to East.
♠
A J
Example 2 North to lead
♥
—
♦
—
♣
2
N
E
S
♠
K Q
♥
K
♦
—
♣
—
♠
4
♥
Q
♦
—
♣
A
However, if instead, South plays the ♥2 to the ♥A, East is squeezed when declarer next leads the ♣2 to the ace.
If East discards the ♥K, declarer cashes the ♥Q discarding the ♠J and leads to the ♠A.
If East discards the ♠K or ♠Q, declarer cashes the ♠A and ♠J.
♠
A J
Example 3 South to lead
♥
—
♦
2
♣
—
N
E
S
♠
K Q
♥
K
♦
—
♣
—
♠
4
♥
Q
♦
—
♣
A
In this layout there is no way to get back to the hand by playing the ♣2 to the ace. In this case, the ♥A must have been cashed already at an earlier stage to squeeze East when declarer leads the ♣A and discards the ♦2 from the table.