In the round of 16 of the open trials, you must decide how to handle a 2-suiter at a high level.
None vul, West deals. As South, you hold:
4♠: Not necessarily weak, since the 1♠ opening is limited.
Your possibilities other than passing or bidding 5♥ directly are:
Double: Primarily penalties. Partner is expected to pass unless he has unexpected distribution.
4NT: Either 3-suited, or 2 suits one of which is hearts.
4NT looks very clear. Your hand is quite offensively oriented with the 6-5 shape and the spade void. If partner bids 5♣ you will pull to 5♦, showing a red 2-suiter.
You bid 4NT. The bidding continues:
West's double opens up new options. Partner wasn't forced to commit himself. He was able to pass, giving you a chance to describe your hand. You can bid 5♦, of course, showing the red 2-suiter. However, you can do better. Instead, you can redouble. Partner will initially think that you have a 3-suiter. When he bids the expected 5♣, you will pull to 5♦. This sequence logically shows the proper emphasis on hearts. By contrast, an immediate 5♦ call shows diamond emphasis. This will allow partner to choose the better strain.
If East doubles partner's 5♣ call, you can do even better. Now a 5♦ bid would show that your suits are about equal, while a redouble would show definite heart emphasis. Partner will know from your failure to bid an immediate 5♦ that you don't have definite diamond emphasis.
You choose to bid 5♦. The bidding continues:
Should you go back to your stronger suit?
You have made your bed, and now you must lie in it. While you failed to show your heart emphasis, you have shown a red 2-suiter. Partner has chosen diamonds, and for all you know he could be quite short in hearts. You must pass.
You pass, ending the auction.
West leads the ♠A.
It can't do any good to discard a club, since the opponents will just continue spades. You ruff. How do you play from here?
If you had no information, the percentage play in the diamond suit is diamond to the king and finesse the ♦J. This allows you to pick up ♦Qxxx in East's hand. However, you have plenty of information. West doubled both 4NT and 5♦. He certainly isn't doing this with a singleton diamond opposite a partner who might be quite weak. West definitely has the diamond length, and probably has the ♦Q.
If you had sufficient entries and chose to play West for the ♦Q, the proper play would be to lead a diamond to the jack without cashing the ♦A first. This would allow you to pick up ♦Qxxx in West's hand. Here you do not have sufficient entries, so you might as well cash the ♦A first just in case East has a singleton ♦Q. If both opponents follow small, you will then take a diamond finesse.
You cash the ♦A. Both opponents follow small. You lead a diamond to the jack. East discards a spade. Now what do you do?
West has shows up with 4 diamonds and at least 5 spades, so it is clearly percentage to play East for heart length. West doesn't need the ♥Q for his bidding. If anything West is likely to be short in hearts, and was banking on a bad heart split to defeat 5♦. Cashing the ♥K planning on finessing has to be the right way to play the heart suit.
There is no reason to draw a third round of trumps. If you do and the heart finesse happens to lose, West will be able to draw your last trump and run his spades. You must leave the ♦K in dummy for damage control. It won't matter if West gets to ruff a heart, since West has a trump trick coming in any event.
You lead the ♥K. West ruffs, but that is the end for the defense. The best West can do is lead a club, but you can win the ♣A, draw his last trump, and ride the ♥9 so you can repeat the marked heart finesse. All you lose is a club trick in addition to the diamond loser. The full hand is:
What do you think of West's doubles?
The double of 4NT looks like a serious error. It has several strikes against it. Most important is that from West's point of view N-S figure to land in 5♥. West doesn't want to induce East to double 5♥. If East can't double 5♥ on his own it might be better to compete to 5♠ as it is on this hand.
Another disadvantage of the double is that it gives N-S more maneuvering room. If West had passed, North would have to bid 5♣, South would have to bid 5♦, and North would be on a blind guess as to which red suit to play. The double of 4NT gave South a chance to show heart emphasis and get to the superior 5♥ contract.
A third disadvantage of the double is that future doubles might tell declarer how to play the hand. This is exactly what happened. If there were no further information, declarer might well have gotten the diamonds wrong and gone down.
After having doubled 4NT, the double of 5♦ was okay. Since N-S failed to choose hearts it appears that East has good hearts, and that 5♦ will be going down. However, if the opponents did properly choose diamonds East will be short in diamonds, in which case 5♠ just might be making.
The concept of the slower auction emphasizing the higher suit in scrambling auctions is a common concept which comes up quite often. For example, suppose the bidding goes 1NT-P-3NT to you, you have a major 2-suiter, and decide to compete. Instead of guessing which suit yourself, you can try bidding 4♣. This will undoubtedly get doubled. Now with longer hearts, you can go directly to 4♥. With longer spades you can redouble, and if partner bids 4♦ you can redouble again. With equal suits you can redouble, and then bid 4♥. Partner will know just what you have and be able to choose the right trump suit.
Plus... it's free!