Vienna coup

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 after observing it being executed in the days of whist by "the greatest player in Vienna" — identity unknown.

Examples

On the play of the by South, East is squeezed but can escape by throwing a small heart. Although the is now set up, South must next play either the, or 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 the to the, East is squeezed when declarer next leads the to the ace.
In this layout there is no way to get back to the hand by playing the to the ace. In this case, the must have been cashed already at an earlier stage to squeeze East when declarer leads the and discards the from the table.