Gunnar Hallberg is not only one of the best players around, he is also a fine analyst, with a good eye for a deal. He sent me this apparently simple board from an online teams game, telling me that both his partner and his opponents could have done better. But now you are warned, you won't fall into the traps, will you?

At the table the contract of four hearts received a top club lead. Declarer won the ace and drew trumps, then stripped off the clubs, and led a diamond to the king and ace. Back came a spade to the jack and queen and West cashed his diamond winner then played a second spade; 10 tricks made.

The defensive error is easy to spot; had West underled his diamond queen, East would have won his 10 and played a second spade, for down one. But declarer’s slight slip is far harder to spot. He could surely have made the defenders’ life more difficult if he had given up on the overtrick after winning the club king at trick one. After taking out the trump and leading a club to the king, a low diamond from dummy would have made East’s life VERY hard. He needs to go in with the 10 to have any chance to set the hand. Be honest, would you have found the play?

I suppose one could argue that the play is unlikely to cost; but I’m not sure I would see the position coming unless I was very wide awake.

When this deal occurred at my local club, I was interested in the variety of play and defense that took place. At my table West led the club king, requesting count. East showed a doubleton so I won the second club and led the diamond jack from my hand. East won this, to play a heart, and I took the trick in hand and led the diamond queen. When East shrewdly ducked, I cashed two hearts ending in dummy, took the spade finesse, then threw East in with a diamond. He could cash his long heart but I took the last three tricks with two spade winners and a diamond.

At other tables West was allowed to hold the first two club tricks. A third club now was pointless, so West looked to try to set up a trick for his partner. The heart nine turned out to be the winner, since East was able to get in twice more in diamonds, and establish a fifth winner for his side.

But note that to defeat the hand East still needs to keep declarer out of dummy for the second spade finesse. So he must duck either declarer’s first or second high diamond, or declarer can come to three spade tricks, three heart tricks, two diamonds and a club.

(As an aside, it is very useful against no-trump to have the specific leading agreement that one of the ace or king asks for attitude, the other shows a good suit and requests the unblock of an honor, or a count signal – high for even, low for odd.)

There are plenty of people at the Dyspeptics Club who would consider raising one spade to two as East, to muddy the waters for the opponents, but at unfavorable vulnerability today's East was not amongst them. Accordingly North-South had a relatively free run to four hearts, against which West cashed his two high spades and shifted to a passive trump. That left declarer free to tackle the hearts and clubs as best he could, without any help from the opponents. At the table he saw no need to look further than drawing trumps and advancing the club king. West took the trick and continued with his passive defense, by returning a club.

Now South tested clubs first, then when they failed to behave he took the diamond finesse, and was more hurt than surprised when it lost.

South was about to start lamenting his bad luck when he noticed from his partner’s premature gloat that this would be inappropriate. Untypically, he asked his partner if there was anything he could have done, rather than trying to absolve himself from blame. What was the response?

South should have drawn trumps ending in his hand then led a low club toward the dummy. West cannot gain by taking the trick and having his ace fall on empty air. But when he ducks, he is thrown in at the next trick with the club ace, to give a ruff-sluff or lead diamonds for declarer. Either way, 10 tricks result.

Some of the clever plays found by experts are absurdly simple. Watch Zia Mahmood at work in his contract of six no-trump. West leads the spade 10, you play low from dummy, East contributes the jack and you win the ace. Plan the play before reading on.

The obvious thing to do is lead a heart to your king, but can you see the extra chance spotted by Zia? At trick two he played the spade six from his hand and ran it when West twitched, then played low. That was his 12th trick immediately. Zia was confident that East would not have played the jack unless he had to, and West did not see the need to split his honors, but learned the hard way that it never pays to underestimate your opponents.

Zia might still have succeeded had West split his spade intermediates. Ever the showman, he would have seen that he could make his slam by playing West for the heart ace. If he runs all his winners coming down to a three-card ending (where in his hand he holds the singleton heart king and spade Q-7) West either has to discard down to the singleton spade nine, allowing Zia to run the spades, or else come down to the singleton heart ace, in which case Zia could exit with a heart to endplay West into leading a spade.

We cannot be sure Zia would have played the hand this way, but in my experience it does not pay to bet against him.

Put yourself in East's shoes and see if you can do the math in today's deal.

When South jumps directly to three no-trumps over one club, West leads the spade jack and your first question is what is South’s likely distribution? Very probably he has 3-3-3-4 pattern with a minor and 13-15 points — possibly a 12-count with good intermediates. Declarer wins the lead in dummy, and calls for the club queen. Your ace holds the trick.

Now is the time for some more counting. Dummy has 13 points; you expect declarer to have about the same, and you have nine. Partner can have only one significant high card, thus the only suit that could produce three winners for your side is hearts. If you lead a low heart that will do the job at once if partner has the king, but if what declarer has that card and partner has the heart 10 plus an entry in the form of the club king? Now leading the heart ace won’t do the job, nor will the eight or nine, as declarer will run that to the jack.

The only card to help your cause is the queen. If South covers with the king, partner is well-placed to play his heart 10 through dummy’s jack when in with the club king. And if South ducks, a low heart next will keep defensive communications open and lead to five tricks for the defense.

In today's deal the slip that declarer made was an elementary one, but the play seemed so straightforward that many players would relax, expecting to have 10 tricks on top, and would not see the significance of their mistake.

Against four spades West decided to go for a forcing defense by leading the heart ace then queen. It looks normal for South to take this with the king and discard a club from hand, assuming that he would simply lose the two minor-suit aces in the fullness of time.

This was what our declarer did, but he paid for his carelessness by going down. He drew two rounds of trump to find the bad news, then advanced the diamond king, and West won the first diamond (if he ducks, declarer reverts to clubs and survives unscathed) and played a third heart to reduce declarer to trump equality with him. Now declarer tried the club king. When East ducked, declarer played a second club and East won and gave his partner a club ruff. Had declarer drawn trump before playing a second club, the defenders could have run the hearts when in with the club ace.

The correct discard at trick two is a diamond. Declarer then draws trumps and continues by playing on clubs. The defenders can take their ace and force declarer again, but he runs his winners and concedes trick 13 to the diamond ace. In retrospect it is hard to imagine why one would take any other approach…and yet, the mistake is hardly an unreasonable one.

Early last year eight pairs took part in the Belgium open team trials for the European Championships in Opatija, Croatia, which took place last July. The top three pairs would qualify through an exhaustive round robin process over a seven day period, and with one day to go, those top three places seemed decided. However, the third-placed pair (Philippe Coenraets and Steven De Donder) were overtaken at the death by Patrick Bocken and Olivier Neve. This was the decisive board in their individual encounter.

After the lead of the diamond king and ace against Neve’s five clubs (East showing an odd number), West switched to the spade queen. Neve took the ace, and realized that East rated to have seven spades and three diamonds; thus he would have to be short in one of hearts or clubs. Since North-South had nine clubs and seven hearts between them, it was far more likely that East’s shortage was in clubs.

So South cashed just one top club, then played the heart ace and queen, and finessed the heart 10 as East helplessly discarded. Now he could take the heart king to discard a spade, and ruff a spade back to hand. Finally he could take the marked trump finesse for an impressive plus 600. Note that if declarer uses his heart entry to take the early finesse in trumps he can never get back to hand to take the heart finesse.

Defense is a partnership effort, and suit preference is a way for the players to cooperate, by suggesting a line of play to your partner.

Here, for example, as West you lead out the heart king and ace, partner playing the eight followed by the club two (discouraging and suggesting a five-card suit if he is signaling count). It is up to you to plan the defense from this point on when giving your partner the ruff.

A diamond play can never really help your side, can it, since declarer is marked from the auction with all the missing high cards? When South balanced with two spades he showed that he surely has both high diamonds and relatively solid spades. So if you signal for a diamond and partner obediently plays one (which would be right if you had the diamond and spade kings instead of your actual hand) declarer would win in hand and drive out the spade ace, then take the club finesse for his contract. There is nothing that you can do to prevent him from bringing clubs in for the discards he needs.

The correct thing to do is to play the heart three, asking partner to return a club. Then if you continue a club when in with the spade ace, declarer can never make more than two club tricks and you will score any diamond tricks to which your side is entitled. An alternative might be to shift to a club yourself at trick three…unless declarer started with a singleton!