Source: Wikipedia

The Vienna coup is an unblocking technique in contract bridge made in preparation for a squeeze play. 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.

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 theQ is now set up, South must next play either theQ,2 or4 to be won in dummy and has no entry back to cash it; he must now lose a spade to East.

However, if instead, South plays the2 to theA, East is squeezed when declarer next leads the2 to the ace.

A J Example 2
North to lead
2
N

                 E

S

K Q
K
4
Q
A

 

  • If East discards theK, declarer cashes theQ discarding theJ and leads to theA.
  • If East discards theK orQ, declarer cashes theA andJ.
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 the2 to the ace. In this case, theA must have been cashed already at an earlier stage to squeeze East when declarer leads theA and discards the2 from the table.