In the round of 16 of the open trials, you face a difficult opening lead problem.

E-W vul, West deals. As West, you hold:

2♦: Artificial 4th suit, forcing to game

Your lead. Attitude leads vs. NT. From honor holdings, ace from AK, king power lead, Rusinow from lower sequences with 8 being the swing card.

A club lead into their 4-4 fit doesn't make sense. A spade lead might set up some tricks, but it also might give declarer a finesse he wouldn't be able to take for himself. A heart lead is safe, but may lose an important tempo.

A diamond lead could well work. Partner figures to have some diamond length, since South has spades and clubs and North has hearts and clubs. Partner didn't double 3♦, but he wouldn't be doubling for a lead with something like Jxxxx.

It is often correct to lead the queen from AQx. The idea is to force declarer to take his king so if partner has Jxxxx you will then be able to run the suit. If you lead the ace, declarer will be able to hold up from Kxx. However, this is necessary only if partner doesn't have an entry. On this hand you must assume partner has an entry, or you aren't going to defeat this contract. Therefore, you might as well lead the ♦A. This will avoid giving declarer a second diamond trick if declarer has Kx and dummy Jxx, which is quite possible. Also, the appearance of dummy and partner's signal may indicate that a shift is called for. You don't have to commit yourself at trick 1. It is easier to defend when you are looking at 26 cards than when you are looking at 13 cards.

You lead the ♦A.

Partner plays the ♦4 (standard attitude signal at trick 1 on honor lead vs. NT) and declarer plays the ♦6. What do you do now?

What do you know about South's hand?  He definitely has at least 4 clubs for his 3♣ call. He has at least 4 spades, probably 5, since partner didn't bid over the 1♥ call and with 4-2-3-4 shape East might not have bothered showing the club support.

The ♦2 is missing, Partner could well have been encouraging diamonds, with the ♦4 being the highest spot he could afford. This would be consistent with East having 5-2-4-2 distribution.

Could it be right to continue with the ♦Q, playing partner for K10xx or K9xx? That is possible. But you would still need another trick to defeat the contract. If partner has a heart or club entry, it won't be necessary to cash the diamonds.  What if partner has the ♠A, and declarer the ♥Q and ♣AKxx or ♣AJ10x? Now cashing out is necessary. This would give declarer something like ♠KJxxx ♥Qx ♦10x ♣AKxx. Would declarer have bid 3NT with that hand? He can't know that his partner has such a good diamond holding -- in fact, many players would raise 2♦ to 3♦ with that hand, showing the 0-5-4-4 shape. South would certainly have bid 3♥ with that hand, keeping open the possibility of playing in a 5-2 heart fit with the diamonds unstopped.

It looks like declarer has at least Kx of diamonds. Would partner have encouraged in diamonds with ♦10942? Yes, he would. You lead ace from AK vs. notrump, so from his point of view you have AKx of diamonds and he wants diamonds continued to set up his fourth diamond before his entry gets knocked out. And it is always possible that declarer started with K62 of diamonds, in which case continuing diamonds is really disastrous.

So, what should you shift to? Either black suit might cost a trick, and it doesn't look like you can establish enough quick tricks to defeat the contract. A passive heart shift looks best. Partner could have the queen. Declarer won't have any particular reason not to take the finesse, since from his point of view you are just trying to find a safe exit.

If you do shift to a heart, you should lead an honest ♥9. This won't mean anything to declarer, but it might to partner. If partner has the stiff ♥Q and declarer finesses, partner will know from your ♥9 shift that declarer has only 3 heart tricks. This knowledge might help partner's defense.

You shift to the ♥9.  ♥J from dummy, and partner wins his ♥Q. Partner leads back the ♦2 to declarer's king. Declarer leads a heart to dummy and cashes another heart, partner discarding the ♠4 and ♠5 and declarer the ♠2. Now declarer leads a club to his ace (♣6 from partner), cashes the king of clubs (♣10 from partner), and leads the ♣9. What do you discard?

Obviously you can't afford to discard a diamond or a heart. It seems normal to discard the ♠7.

You discard the ♠7. Dummy's queen of clubs wins, partner playing the jack. Now the ♣8 from dummy. Partner discards the ♦9. What do you discard now?

It is clear that partner has the ♠A, as otherwise declarer has 9 top tricks. Once again you must discard a spade. However, the ♠Q might be a liability. Suppose, for example, partner started with ♠A10854 of spades. If declarer cashes the heart he is down, so he will exit with a small diamond to your queen. You must lead your last spade, of course. If you still have the queen, partner can't afford to overtake since declarer would have 2 spade winners. And now declarer, who will have a count on the hand, will also duck and you will be forced to give dummy the last 2 tricks.

It is vital that you discard the ♠Q. Now when you lead the ♠9 partner can overtake with the ♠10, and it is the defense which is victorious. The full hand is:

Unfortunately, it didn't quite happen this way. East lost the thread and discarded a third spade on the last club, hoping to fool declarer about the diamond position. Now the defense had no chance when declarer exited with a small diamond from dummy.

Should declarer have done better?

Yes, declarer should have done better. Instead of cashing the fourth club, all he had to do was lead a small diamond from dummy while he still had the ♣8 entry. There was no reason for him not to do this. All the evidence pointed to West having started with AQx of diamonds, and if that weren't the case declarer had no realistic chance anyway.

Aside from the bad spade discard by East, could the defense have been improved on after the opening lead?

The heart shift was fine. East's diamond return is normal, since from his point of view West started with AKx of diamonds and after West wins and plays a third diamond the defense would take 1 heart, 1 spade, and 3 diamonds while declarer takes only 4 clubs, 3 hearts, and 1 diamond.

However, there was a small slip-up. West's first discard should have been the ♠9, not the ♠7. To see why, imagine that declarer started with KJ832 of spades. In the ending West will be down to a stiff ♠9. East cannot afford to overtake, and once again declarer ducks forcing West to give dummy the last 2 tricks.

It may seem as though the same position arises if West retains the ♠7, as once again East can't afford to overtake and declarer can duck. But something funny happens along the way. Let's look at the end position.

When declarer leads the diamond off dummy, which spade does he discard? If he discards the ♠3, he can no longer duck West's ♠7. If he discards the ♠8, now East can afford to overtake with the ♠10 and will get 2 spade tricks. This is one of the most unusual variations of a one-suit squeeze I have ever seen.