A tough hand. Guess you just can't make it on the king of spades opening lead. Even so, there are a few comments to be made about the way the hand was played, even with a couple who got that deadly opening lead. You can't make it, but you can come closer, and if anyone scoffs at that, next time the play that could have brought you closer might be a winning play.
Anyway, let me first refer to the declarer, playing from the opposite side of the table, who got the ace of diamonds opening lead (!) and then a diamond continuation (!), with the 10 holding the trick. How could one ask for anything more? The problem was, this declarer sluffed the 7 of hearts on the 10 of diamonds! ! ! Pul-eeze! That 7 of hearts is a winner. It can become a winner in its own right (after ruffing three rounds of hearts, the only way to make the hand without a diamond continuation).
You must see that you've got a spade loser you can't afford, in view of the ace of diamonds out against you, and ask how you can rid yourself of spades beyond the first round in one hand or the other. Here it's not enough that one spade goes on the queen of diamonds, for you'd then have a low spade in each hand. However, the ace of diamonds was a gift anyway, because now you've got ruffing entries to facilitate ruffing out the hearts and the ace of spades for cleanup when you've established the 5th heart on which you'll sluff a spade, thus: A of hearts, ruff a heart, back with a trump lead, ruff a heart (everybody following means you've got the desired 4-3 split). Back with a trump lead, ruff a heart, back with the A of spades, sluff a spade on the long heart. You'll now ruff a spade (the closed hand's last trump), throw a spade on the queen of diamonds and dummy is now good with two trump. Suppose East leads a trump at trick two. You have substantially the same play, only after one return to that hand with a trump lead, you would now ruff diamonds.
That's if East shifts to anything after cashing the ace of diamonds. But this East wasn't done with his generosity. He continued diamonds, allowing declarer to sluff spades on the 10 and Q of diamonds. Now declarer will ruff a spade in dummy, forget the hearts and soon claim a good closed hand.
Pul-eeze don't discard your winners on a winner in the other hand. You've got to git rid of losers, and the second round of spades is certainly a losing round for declarer unless he can sluff two of dummy's spades on the Q 10 of diamonds or one spade in the closed hand on dummy's fifth heart, the very card this declarer sluffed! (Well, not the "very card," since you'll probably ruff the 7, 8 and 10 in that order, but as the fifth heart, it's the "very card" declarer should save.)
Had East led anything but a diamond at trick 2, establishing the 5th heart would have been feasible, But the diamond follow-up, allowing declarer to test the 10, should have made the hand a cakewalk.
I hafta refer to a declarer in 3 no. As I looked at the hand, I found eight top tricks, with a certain trick to be established in diamonds, and no way the defense could run either of the major suits without giving up a trick first, that seemingly insignificant 10 of spades being a guarantor of that. I had to see how this declarer managed to go down and didn't have to go beyond trick one: Opening lead a low spade, up with the ace and . . . and what? You just have no 9th trick now.
What happens if declarer ducks and East holds both the K and Q of spades. East wins and then what? He doesn't want to lead into the A J of spades, does he? He can't hurt you in diamonds, since that's the suit where you've got a 9th trick coming. Clubs? Obviously not. You win and lead a diamond. And hearts? It'll take a lead coming from East into the A J 10. If West goes up, you win and lead the jack of hearts and there's your ninth trick.
Please. You've got to look at your whole hand, count your winners, look to see where another might come from, note dangers, of course, and play accordingly. It's not that we can see that the 8 or 10 could win the opening lead for a 9th trick right here, a 10th being available on a diamond lead. I've outlined above what happens if East wins the trick and we find nothing dire at all. Nothing at all. You've got to think of your 9th winner (and maybe a 10th, as just referred to, if feasible).
And, oh yes. This declarer, a Life Master who keeps popping up with grist for my mill, starting with trick two ran six clubs! I say again and again and again. When you run your long suit, unless you're ready to cash out, you're far more likely to harm yourself than the opponents! Yes, there are bound to be cases where a few declarers get a faulty discard on declarer's running his best suit. Still, I never said you'll never benefit thereby. I've only said you're ten times as likely to harm yourself than your opponents. You've got to develop your necessary winners when there's no danger and there are winners you can develop.