As it was, he had to abandon diamonds and do something with the spade suit.

South was expected to bid a four-card spade suit and did.

South has enough tricks if he can prevent East from establishing and using his spade suit.

There was no longer any way to bring home the spade suit, and the contract had to fail.

Cue-bids made it clear that there was a problem in the spade suit.

South now knew what had happened in the spade suit and put up the ace.

East finally opened up the spade suit and led the four rather than the king.

This offered some chance of 11 tricks, but ran an obvious risk in the spade suit.

With the spade suit exposed, North retreated to four diamonds.

A diamond lead would have been best, but West led the unbid spade suit.