You reach 4♥ after East opens 1♠. West leads the ♠3 to East's nine and your ace. What is your play to trick two?

Solution:
You have six heart tricks, one spade trick, and can score two diamond tricks, which adds up to nine tricks. The ♣A can serve as a tenth trick, but there is no immediate entry to cash it.

Thanks to the presence of the ♦J, dummy may not be entryless after all. Your correct play at trick two is the ♦Q. East can take the trick with the king and cash two spades, but you will ruff a third spade high, draw trumps, enter dummy with the ♦J and finally cash the ♣A. If East refuses to take the ♦K at trick two, you will play the ♦A, ruff a diamond in dummy, cash the ♣A and end up with an overtrick!

Analysis:
Bridge Baron's double dummy solver confirms that leading the ♦Q at trick two is required to score ten tricks. However, if declarer does not find the right play, the defenders still have to be on their toes to beat the contract. If declarer runs his hearts, West cannot let go of a diamond (otherwise declarer can score three diamond tricks), and East has to discard his three clubs followed by a diamond (if he discards a spade, he can be endplayed in spades and will be forced to concede an entry to dummy).
Par Contract Analysis:
The par contract is 4♥ by North-South.

Bridge Baron deal No : N1080-95409-52296-06581-15099-14931