You are South on this week's deal, declaring an excellent 4♥ contract. West leads the ♠K, won by dummy's ace. First things first, you play two rounds of diamonds, discarding your spade loser. You choose to continue with a third round of diamonds, discarding a club. How should you proceed?

Solution:
If trumps divide 2-2, you will make the contract no matter what. The 3-1 split in trumps is the situation you should cater to. The obvious continuation is to lead a club off of dummy - if East has the ♣A, you are in good shape. If West has the ♣A and one opponent holds the singleton ♥K or ♥A, you will still be fine. However, if West has the ♣A and one opponent holds AKx of hearts, the opponents can play three rounds of trumps and you will go down.

There is a line of play to counter the particular scenario where one opponent holds the singleton ♥8. It involves making the key play of ruffing a diamond to establish a winner in the suit. Establish a winner in a dead dummy seems pointless. But dummy is not really dead! After ruffing a diamond in hand, you play the ♣K. The opponents can lead three rounds of hearts, but you will unblock two high honors, and win the third round in dummy with the ♥7. The established diamond takes care of the club loser in hand.

So which of the above two lines should you adopt? The clue lies in the bidding. West has made a takeout double, and therefore is a favorite to hold the ♣A; he is also likely to be short in hearts. Therefore, ruffing a diamond and playing a high club is marginally better than the other line.

Analysis:
According to Bridge Baron's double dummy solver, ruffing a diamond at the critical point is necessary to make the contract on the actual lie of cards.
Par Contract Analysis:
The par contract on this deal is 4♥ by North-South.

Bridge Baron deal No : N4290-31058-28032-80124-09372-75965