Hand 5

From actual play (matchpoints, opponents not vulnerable): You pick up a nondescript:

876
K42
KJ84
Q98

The auction is:

 
RHO  you  LHO  pd
P     P   1S   P
1NT   P   2D   P
P     P

The 1NT was forcing. A 2S rebid by opener would show six spades. The 2D bid promises at least 3 diamonds, and almost always more diamonds than clubs. Defending in diamonds is a pleasant surprise.

Partner leads the Q, and dummy comes down with

Q5
965
Q7653
AJ6

You are supposed to have time to think after dummy comes down. Use it.

Declarer has five spades and your partner four. Unless declarer has all four of the remaining diamonds, declarer has three and your partner one. That give declarer two clubs (with more, declarer would have been 2 clubs; with less, declarer would have four hearts and would have bid 2 Hearts. That leaves declarer withe three hearts (and partner a 3-4-1-5 distribution).

You play the 4, trying to be encouraging. Declarer wins with the ace and plays A, all following. (If your partner had shown out, you could have to recalculate.)

So, unless declarer decided to do something odd, declarer is 5-3-3-2. You should plan on that unless something happens to disprove it. You have two diamond tricks for sure, and you are one-spot short of making your 8 good.

Declarer, not yet knowing about the bad diamond break, then leads the 10, playing small from dummy. Your partner shows out, as you expected, pitching an uninformative club. You win with your J.

No probems yet: You play your K, winning, then a small heart. You partner wins with the J.

Partner then leads the 10. Declarer wins the ace and leads the Q. Partner wins with the king and leads a small club. Your 8 of clubs wins.

Now what?

Placing the High Cards

Declarer has the Ace of diamonds, Ace of Hearts, and nothing in clubs. So declarer has to have the A of spades. Declarer played the suit as if also having the jack of spades.

Now it is a double-dummy problem, albeit a relatively difficult one for the bridge table:

             x
             --
             Q76
             J
xx                     xx
10                     --
--                     K8
Kx                     Q
             AJxx
             --
             10
             --
If you return a spade, you probably get only your king and declarer is down 1.

But iff you lead a club, declarer has to ruff with the 10. that promotes your 8 of diamonds to a trick, for +100.

But, if you cash your king of diamonds, you can now cash a club trick. That is also down 2. And if your partner overtakes your queen (as he should -- partner can count the hand too), he can lead his last heart. Then you make your 8 en passant. Down 3 and +150.