In the round robin of the U.S. trials to select the international squad to go to Bali for the 2013 Bermuda Bowl, the following declarer-play problem came up. It was not accurately solved by any of the participants who were confronted with it.

Say you reach four hearts and receive the lead of the heart nine. It looks best to win the trick in dummy and start to eliminate the club suit by leading a low one from the board, which is won by East’s 10. East now exits with the diamond jack. Since the contract is only in jeopardy if diamonds do not break, it looks simple enough to win the diamond ace, trump a club, and lead the heart queen to the ace.

Declarer should then continue to prepare for the endplay he might need if diamonds do not cooperate. Best is to play the spade six from hand, and duck when West plays his seven. West is allowed to hold the trick and exits with the diamond queen, bringing the bad break to light. Declarer wins his king, plays a spade to the ace, crosses to dummy with another heart, and plays the spade jack, discarding a diamond from hand.

Poor East must win the trick and now has no choice but to lead a black suit. That gives declarer a ruff and sluff, which can be trumped in dummy as declarer discards his last diamond loser — making four!

The most straightforward hands sometimes offer a chance for whimsy. In this deal from last year's trials for the national squad to go to Bali, most North-South pairs ended up in three no-trump, here after a strong no-trump by South. If a diamond is led, the defense will surely take the first five tricks, but on any other lead, the contract rolls home.

However, declarer has a curious resource if the diamond seven and eight are interchanged between the South and East hands to produce the diagram as shown. (In real life those cards were switched). Now, when West leads the diamond five to East’s queen — a much better play than the ace at the first trick if partner has jack-third in diamonds — South follows with the deuce. East returns the diamond six and South imaginatively follows with the JACK!

West wins the king perforce, and returns his remaining diamond, the nine. If West started with an original K-9-8-5, East must duck now to avoid blocking the suit and taking only four tricks. On the other hand, if West started with K-9-5, East must take his queen to avoid taking only three tricks in the suit.

There is no scientific way around this problem. If you sacrifice potentially useful spot cards on opening lead to avoid blockages, you will cost yourself tricks in other more normal layouts of the cards. The simple solution is to hope that you do not come up against declarers who are as ingenious as today’s.

In this deal from the 2013 U.S. trials, six clubs has to be played by South, or else a diamond lead through the ace-queen would be fatal. How would you play the slam on a heart lead?

You must avoid leading a spade to the king and ace, or else a diamond return will put you on the spot. Are you going to play for the diamond finesse or for spades to behave? Best is to win the lead in dummy and lead a low spade from the board toward your queen. If West wins the trick, you get to test spades before playing on diamonds. But if it is East with the spade ace, he is caught in a Morton’s Fork Coup.

East cannot fly up with his ace, or declarer can establish three discards for dummy’s diamonds on the top heart and two spades. So East ducks the spade, whereupon declarer wins the queen. Now he discards the spade loser on the hearts, and is almost home. As the cards lie, he can simply draw trump and give up a diamond.

But it is best after pitching the spade loser to play the diamond queen from hand. If the defenders take this, you can unblock diamonds and draw trump. If the diamond queen is ducked, you take two top trumps from hand, and claim if clubs split. If they don’t, you cash the diamond ace, draw trump, then give up a diamond for your 12th trick.

Today's problem was encountered by a declarer in the American trials for the World Championships in Bali.

Declarer was playing against an expert and aggressive pair. In three no-trump, on the lead of the heart nine, dummy’s jack lost to the king. Back came a second heart, won in dummy, and South then led a club to the king, which held. What next?

Declarer led the diamond nine to the ace, then finessed in diamonds, discovering that his Right-Hand Opponent had started with four diamonds to the Q-10 when his Left-Hand Opponent threw away a spade. What now?

Declarer went after spades, but East won his ace and cleared the hearts, while West still held the club ace as an entry — down one. The defenders were Denny Clerkin (West) and his brother Jerry. The key to the defense was that when declarer led a club to the king at trick three, Denny ducked without a flicker in a successful attempt to preserve his entry.

It is easy to be wise after the event, but it was probably right for declarer to continue playing on clubs at trick five, unless South deemed West incapable of ducking an ace. If West wins the club ace at his second turn and clears hearts, declarer will go after spades. But if East can win the club ace and then clears hearts, declarer should play on diamonds. East probably does not have two aces and a king, or he would have opened the bidding.

The names have been omitted in today's deal from last year's trials for Bali to protect the guilty.

Against four spades West led his singleton diamond. Declarer won and played ace and a spade. West followed with the 10 on the first round, then won the queen and returned the heart three (conventionally, lowest from an odd number). Declarer won the ace and led a club to the king in dummy. The first mistake came when East won the ace, despite West’s echo to show an even number of clubs. East should know that declarer must have exactly three diamonds. Partner must have five hearts, giving declarer one heart. So, declarer must have exactly two clubs. Best defense is therefore simply to duck the first club, eliminating dummy’s entry to the clubs.

Now for mistake number two: East returned the diamond queen instead of a heart. Partner can’t possibly need a ruff, since he followed with the spade 10 and queen. Leading a heart would have clarified the situation for partner.

Declarer played the diamond king and now West trumped in, rather than waiting for a possibly useful discard from partner. When he exited with the heart queen rather than playing a club to break up the squeeze, declarer ruffed it and ran the trumps. This squeezed East between the club jack and his master diamond.

In the ending, declarer had to guess what to do in clubs, and he did — at least SOMEONE did something right on the deal!

Today's deal from the most recent American trials was generously reported by the victim of proceedings, Christal Henner-Welland. After stretching more than somewhat to respond one no-trump at her first turn (in competition the typical range for this action is 7-10), South was treated to a small-heart lead in three no-trump, and she won East's nine with the queen.

Now, should you play the clubs from the top, or finesse? Playing off the top clubs looks right to me; if West wins the club queen, there is no return he can make that will hurt you. As against that, if West has the club queen and East had ducked the heart king, you will end up with egg all over your face.

At the table, South elected to run the club 10 at trick two, losing to the queen. The spade 10 was returned. How should you play from here? If West started with a small singleton or doubleton, you must cover and win the trick. However, if West started with honor-doubleton, you must duck and the spade suit will be blocked.

At the table declarer ducked, playing for West to hold honor-doubleton in spades. Result: misery. Well done, Roger Lee as East, who overcame his distrustful partner’s opening lead. (The game goes down on a spade lead — but who leads partner’s suit?) When he shifted to the spade 10, he was in effect playing his partner for the spade eight and for declarer to misguess what to do. Clever stuff, eh?

In today's deal, South took two good views, one in the bidding and one in the play.

To start with, he decided that his 5-5 shape would play better in four spades than in three no-trump, and rather than look for alternative strains, he bid the suit game at his second turn. Right he was: The no-trump game can be defeated via repeated heart leads.

Following this, South had to negotiate the play after the lead of the heart five to dummy’s king. Seeing the paucity of entries to his hand, South decided to go after diamonds at once and simply led a low diamond from dummy. He was prepared to concede three diamond tricks — that would still allow him to take 10 tricks if everything else behaved normally.

At trick two, East won the diamond king and continued the attack on hearts. Dummy’s heart ace won the trick, and the diamond 10 was led. East took the trick and played a third heart, forcing South to ruff. It would have done West little good to pitch his diamond jack, so he threw a club, letting South lead a third diamond for East to ruff.

East had no winning play. If he led a heart, declarer would ruff in hand, cash the club ace, then crossruff for the rest of the tricks. On any other return, declarer would simply draw trumps and take his diamond winners.

The bridge columnist who originally reported this deal did so as a kind of mea culpa, airing his sin and hoping for forgiveness. Of course, I will not tell you who it was, but the deal does involve an interesting mistake — and have you noticed that is really the only sort of error that bridge experts make?

The deal, from the later stages of a world championship, featured matching mistakes. Against three spades, West led the club king and ace. When everyone followed, she continued with a third round of clubs. Had East discarded a diamond on this trick, South would have been doomed, but instead she ruffed with the six. This mistake was duplicated at almost every table where three spades was declared.

South overruffed with the eight and too quickly played a spade to dummy’s jack, after which she could not recover. It should have been obvious that the first spade lead needed to come from the dummy, but first she should have knocked out the diamond ace. Say West continues with a heart. Declarer wins in the dummy and now plays a spade to her king. If West follows, life is easy, but if she shows out, South is still in control. She cashes her other top diamond, ruffs a diamond with the jack, then takes the remaining high heart and ruffs a heart. Now declarer ruffs her last diamond with dummy’s spade 10, and East is powerless. Whatever she does, declarer must make two of the last three tricks.