As dealer, You hold the following hand:
♠A K 10 6 ♥— ♦K 6 5 3 2 ♣A J 8 7,
and the bidding goes:
Your left-hand opponent leads the ♥Q, and this is what you see:
When you win ♥A, what do you discard on it? A diamond, of course. Clubs can be played by utilizing the double finesse for split honors, with a 75% chance of success, that is, you play one opponent to have the ♣K and the other to have the ♣Q. It’s possible, of course, that one opponent has both club honors, but the opening lead makes it unlikely that LHO has both. With that holding, LHO may well have led the ♣K instead of the ♥Q, a suit your partner bid.
So do you draw trump at trick two, or do you use the dummy entry for another play? You should play a club at trick two, using the reasoning above. When you play the ♣10, RHO follows low and LHO wins the ♣K. LHO continues with the ♥J, using the principle of doing no harm by risking giving up a trick by breaking a new suit. On the ♥K, you again discard a diamond from your hand and play the ♣9 from dummy. It wins – you have the club suit under control.
Now is the time to start drawing trumps. You play the ♠3 from the dummy, and RHO plays the ♠Q. That is very significant. It would not be surprising if the queen is a singleton, and if so, this means that LHO has J–8–5–2. After winning the ♠Q with the ace, therefore, you should stop drawing trumps. You may want to use some of dummy’s low trumps to ruff your long diamonds. Even if LHO is short in diamonds too, the ♠9 in dummy is higher than the all of LHO’s spades (except the jack, a natural winner for the defense). In general, you have to keep control of the trump suit with a 4–1 break.
Therefore, play a diamond to the queen next, which wins. This strongly suggests that LHO ducked the ace. Next play a club to the ace in your hand, both opponents following. So you lead the last club. LHO trumps low to prevent you from discarding dummy’s last diamond, so you overruff with the ♠7. When you next play dummy’s ♦9 to your king, LHO wins the ace, but he cannot play trumps without giving up his natural trump winner. So LHO plays a heart, which you trump with the ♠6 in your hand. You can then trump your last diamond with the ♠4 in dummy. You can ruff dummy’s last heart, hoping to score the ♠10 in your hand, but leftie overruffs with the ♠J. Your remaining card is the trump ace.
Success! You played every suit carefully and enjoyed 10 tricks even though spades broke 4–1.
Here is the full deal: