The deliberate loss of a trick or tricks in preparation for a squeeze. For most squeezes to succeed, you need to play the squeeze card when you have the ready winners to take all the remaining tricks but one. If you have two tricks to lose, usually the squeeze will fail. However, you can often remedy the situation by giving up a trick before playing the squeeze card.
As South, you play in 6NT and receive the lead of the ♠Q. With eleven top tricks, the contract will be simple if either red suit divides 3-3. You can also succeed if either opponent holds at least four cards in both red suits, for then a squeeze is possible.
However, if you win the opening lead and then cash four clubs, only five tricks will have gone. Each player will have eight cards left, so anyone who started with four hearts and four diamonds will have no difficulty in retaining them and a squeeze will not operate. Instead, you duck the opening lead, win the spade continuation and then cash four clubs.
At this point six tricks will have gone and only seven cards will remain in each hand. Neither defender will be able to retain four cards in both hearts and diamonds. Ducking the opening lead ‘rectifies the count’.