You are West in this week's deal where neither side is vulnerable. The scoring is IMPs and the objective is to defeat the contract. The contract is 2♠, reached via the bidding sequence shown. You have a tough opening lead, and choose an aggressive ♥Q. Partner discourages the lead by playing the two, declarer wins the Ace. Declarer now plays the ♠7, you play low as does declarer, partner wins a surprise trick with the ♠J. Partner quickly returns a heart, which declarer wins with the King. Declarer plays another spade now, you hop up with the Ace, as partner discards the ♦K. What now?

Solution:
Things look much better now, you are in a position to obtain a heart ruff if you put partner on lead. Partner's ♦K discard should deny the Ace (he would have discarded the Ace from the AKQ), and should guarantee the Queen and Jack. Partner has 0 points in hearts, 1 point in spades, the KQJ of diamonds, and he opened the bidding, so he must have the A of clubs. So, you can play a club to partner's Ace, and get a heart ruff. However, it is not good enough to play a small club, the ♣J is the correct play.

Watch what happens if you play a low club. Declarer will play low, partner will win with the Ace and give you a heart ruff. You will play a diamond to partner's Jack and declarer's Ace, but declarer will cross to dummy with a spade, discard his diamond loser on the ♥J and eventually lead up to the ♣Q.

If you lead the ♣J instead, declarer has to cover this with the Queen, parnter will win the Ace and give you a heart ruff. Now you will play a diamond to partner's Jack and declarer's Ace. Declarer can still discard his diamond loser on the ♥J, but he will have to play clubs himself and has to lose two tricks.

Even when partner has the ♣10, playing the ♣J clarifies the position to partner, and makes his life easier. This play can never cost, and has a lot to gain. Declarer made a fatal mistake at trick 2, placing you with the Ace and Jack of spades and running the ♠7. The right play is to play the ♠K, and plan to finesse you for the ♠J on the next round if required.

Analysis:
Bridge Baron's double dummy solver confirms that ♣J is the only good card to play after you won the ♠A.
Par Contract Analysis:
The par contract on this deal is 4♦X by East-West. Since neither side is vulnerable and North-South can make 3♠ in theory (if the ♥Q is led, the contract can make in practice as well), 4♦X is the par on this deal.

Bridge Baron deal No : N0374-00907-71084-20314-48188-90690