Partner leads the ♠K, against 6♦ after South has advertised a long and strong diamond suit. How do you propose to defeat the contract?

Solution:
The winning play is to overtake partner's ♠K with the ace and play a heart. Say the defense continues a spade at trick two. Declarer will ruff in hand, and play the ♦A, observing partner's failure to follow suit. He will then cross over to dummy with a heart, and take the marked diamond finesse against your queen.

If you play a heart at trick two, you remove dummy's late entry. In order to succeed, declarer needs to take a diamond finesse immediately, something he will never do in practice. He will play a diamond to the ace, but he will not be able to do anything about the bad break. If he plays a heart to dummy, you will ruff it, which will be your setting trick.

Analysis:
A double dummy analysis is not applicable to this deal, as declarer can make the hand if he looks at all four hands. Your challenge here was to find a way for declarer to go wrong given that he cannot look at all four hands.
Par Contract Analysis:
Since 6♦ is makeable in theory, the par contract is 7♣X, which is two down.

Bridge Baron deal No : N1698-86718-92820-62701-51915-68903