Today’s deal saw a fine example of premature euphoria being punished. In my experience, there are two common reasons for players failing to find plays they should. These come when things appear to be going so well that they do not consider what might go wrong, or when things are going so badly that they cannot imagine how they might recover from the seemingly hopeless position.

Today, South reached three no-trump without either player having significantly overbid. But on a low heart lead, the outlook did not appear very promising. South nevertheless made the right play when he put up the heart queen. With the heart queen doubleton, there was no advantage to playing low from dummy and forcing a high honor. Meanwhile, putting up the queen would pay off if West had underled the ace-king.

When the heart queen held, South relaxed and cashed dummy’s top clubs, then came to the diamond ace and took his remaining top club before leading a second diamond to dummy’s queen and being disgusted by the result. At that point, the contract could not be made since the diamonds were dead.

The winning line is to cash dummy’s club winners, then lead the diamond king, on which you unblock your own 10 before crossing to the diamond ace and taking the club queen. Now the 4-1 diamond break becomes apparent, and your unblock in diamonds allows you to finesse against West and run nine winners.

Today, you decide to play four hearts, rather than to attempt three no-trump, because of your club fit. West starts out by leading two rounds of diamonds. You ruff and draw all the trumps. How should you continue?

You must try to protect yourself against an unfriendly lie of the cards in both black suits. So you should continue by crossing to dummy with a club in order to lead a low spade toward your jack.

When you lead a low spade from dummy, East wins with his queen and plays a third round of diamonds. You simply ruff and advance the spade jack to drive out the ace. A 4-1 club break is no longer a problem, since the club king will take care of your fourth diamond.

In essence, the recommended line will succeed whenever clubs break, though you may have given up on an overtrick. However, it also succeeds when clubs break 4-1 and either the spade ace is onside or East has both the ace and queen of spades — three-quarters of the possible lies of the spade suit. Leading directly to the king brings home the contract only when the spade ace is onside.

This position would be easier to see if you knew you needed a discard; here, though, that need is not entirely obvious. But if you cash two rounds of clubs before playing on spades, it will be too late to exploit the lie of the spades. You may be able to recover by a squeeze on East, but the recommended line is surely a better one.

Defense is the most difficult part of the game, but in the past, journalists did not tend to write about the principles of defense because it is less glamorous than a well-played declarer hand. This is one of the reasons why past declarers often used to get away with murder.

In 1966, Hugh Kelsey’s “Killing Defence at Bridge” dealt with some of the basics of the game for the very first time, and the book has become a classic.

Today’s deal comes from that book. Against four spades, West leads and continues diamonds, the second being ruffed by South. Declarer plays the spade king, then another spade to the ace, on which East drops the queen. When the heart jack from dummy is ducked to the queen, what should West return?

It appears that, for the defense to matter, South must have started with six spades, and East with queen-jack-third. If East has an ace, it will not run away, but what hope is there for the defense if South has both missing aces and East has one of the kings? Note that a club return is unsafe unless East holds both the king and 10.

If you play a passive diamond, declarer ruffs, plays a heart to the 10, and trumps dummy’s last diamond, removing East’s only exit card. Declarer cashes the hearts, then throws East in with the spade queen, to endplay him in clubs.

A heart return is best, and it defeats the game, allowing East to keep a diamond exit card when thrown in with the spade jack.

Today’s deal was played in this year’s Tarrytown congress. The East and West cards reflect the reward for best declarer play.

North could use fourth suit, then bid spades at his third turn, suggesting four-card support and at least some slam interest. At the table, he chose instead to make a club splinter in support of spades. Both sides then cuebid, but each had weak trumps, so neither could advance beyond four spades.

It was wise to stop there, but if either North or South had slightly better trumps (the 10 in either hand), they would be aware that one trump honor opposite might suffice, and could use key-card to reach a respectable slam.

Assume you have managed to settle in four spades on a diamond lead. It would probably be sensible to duck a spade, then cash the trump ace and play a cross-ruff as your best line for 11 tricks. But what if you are in six spades? Your chances are now extremely slim. Your best bet is to lead a spade to the six at trick two. When East wins his queen and returns a club, you take the ace and ruff a club, then pass the spade jack, pinning West’s 10. This maneuver is known as an intra-finesse.

Assuming East ducks the jack, you next cash three rounds of diamonds, pitching a heart and two clubs, then three rounds of hearts, ruffing in hand. Finally, you cross your fingers and ruff a club in dummy. When that stands up, you take trick 13 with the trump ace.

Barring a revoke, you cannot make a grand slam without the trump ace. That doesn’t mean it hasn’t happened — I have made 13 tricks when the opponents revoked before taking their trump ace, but that is not a course of events you should count on.

A similar feat also requires the opponents to cooperate: Making a small slam when missing three or more trumps that include the ace and king is technically possible but equally unlikely.

In the deal shown, if dummy’s trumps were weaker, with the jack in declarer’s hand, South could lead the queen, hoping that East would naively cover with a doubleton king, but that won’t work today.

On a slightly different deal, leading low from the closed hand might see West rise with his honor from a doubleton holding — but again, that doesn’t seem practical here.

A third possibility actually worked with the cards as they lie. Declarer Ken Barbour found himself in an apparently hopeless slam. Can you find the defensive error he managed to inspire?

Barbour ruffed the heart lead in dummy and led three rounds of clubs, trying to look like a man with diamond losers to discard. On the third round of clubs, East ruffed in with his small trump. South overruffed and led a trump; when the ace and king of spades both appeared, Barbour’s day was complete.

Yes, East should have seen that he had little to gain from this defense. But South gave him the chance to err, and he took it.

In today’s tortuous auction, two diamonds was an artificial game force. After you cue-bid the club ace then rather sportingly showed your heart control (not mandatory with dead minimum high cards and shape for the auction thus far), North drove to the grand slam via Roman Key-card Blackwood.

When West leads the trump five, plan the play and reward your partnership’s optimism.

Clearly, you will need to establish the hearts if you want to succeed. So, after winning the first trick on the table with the trump nine, cash the heart ace and ruff a heart with the king. Both opponents follow — phew! After crossing to dummy with a club, you ruff a heart with the ace. If hearts have broken, you are home free. But if the hearts are 4-2, you need trumps 3-2, as here.

You next throw dummy’s diamond five on the club ace, then cross to dummy with a diamond to the ace to ruff a third heart, thereby establishing two heart winners on the table. At this point, after ruffing a diamond in dummy with the 10, you draw the outstanding trumps with the queen and jack, and dummy is again high.

On this layout, you make four trumps in dummy, three heart tricks and three heart ruffs, plus the diamond ace and two clubs for a total of 13 tricks.

If hearts had been 3-3, you would have thrown a diamond on the club ace, then drawn the outstanding trumps without needing them to break.

When South shows 22-24, North does not hesitate to jump to seven no-trump — particularly since he will not have to play it himself.

Despite the spade wastage, the North-South cards fit reasonably. When dummy comes down, South sees that all he needs to do is find four diamond tricks to bring home the grand slam. He must therefore investigate the side suits to plan his play in diamonds.

South wins the king in hand and begins by running clubs, finding West with three clubs. West discards a spade on the fourth club; East gets rid of two spades. It begins to look as though East started with four or five spades, but before finalizing his plan, South runs the hearts.

When East drops the heart 10 on the third round, it looks as though West started with four hearts and East with only three, though East might be fooling, of course. South leads his second spade, and both opponents follow. Since neither the 10 nor the nine has yet appeared, South should assume that West has at least the 10 for his opening lead of the jack.

Weighing up all the evidence, it seems certain that West started with at least four spades, at least three hearts and the three known clubs. At most, therefore, West can have three diamonds — but he may have fewer.

South can thus ensure his slam by taking dummy’s top diamonds first. When West shows out at the 11th trick, South takes the marked finesse through East to make his grand slam.

After a Stayman inquiry, North jumps to four clubs, a splinter bid showing slam interest with short clubs and spade fit. Once you cue-bid the diamond ace, North drives to the small slam in spades. A diamond lead might leave you in a bad spot, but West leads a trump. Now you must take advantage of your lucky break!

You will need four tricks from hearts to have any chance of bringing slam home, so hearts must break. You can score four trumps, four hearts and the minor-suit aces without a struggle. But to generate the two extra tricks, you must ruff two clubs in dummy.

If trumps are 3-2, you can win the first trick in either hand. However, if trumps are 4-1, you must win the first trick in dummy with the ace. Suppose the full deal looks like the layout shown.

At trick two, you cash dummy’s club ace, but then you must duck a heart. Suppose West wins and exits with a trump. After winning in hand with the jack, ruff a club. Then return to hand with a low heart to the king to ruff a second club. After returning to hand one more time by playing a diamond to your ace, draw West’s remaining trumps with the king and queen while throwing diamonds from dummy. You will take the last three tricks with dummy’s three heart winners.

Caution! If you win the first trick in hand, you will lose either a club trick or a trump, to end up at least one trick short of your contract.