I have four club tricks, two spades, a heart, and a diamond. I need one more trick. Diamonds is the surest place to develop one. But I need two entries to my hand, so I can't afford to guarantee four club tricks by playing low from dummy. That's probably OK. In the unlikely event I cost myself a club trick by rising, I can probably get it back by developing a second trick in diamonds.
I play the ♣Q. (Not the ace, which would announce to everyone that I have king.) East plays the ♣3. I follow with the ♣7. The opponents play upside-down attitude, so, if the carding is honest, the three is either a singleton or is encouraging from ♣Jxx.
I lead the ♦8; East plays the ♦3. I play the ♦5, and West wins with the ♦Q. West surprises me by continuing with the ♦2. He must think I was trying the old trick of attacking my weak suit to talk the opponents out of leading it. I pitch the ♥3 from dummy--♦6--♦9.
The routine play at this point would be to drive the ♦K. But West's diamond play is suspicious. The usual inference when an opponent makes an aggressive, desperate play is that the cards lie favorably for you. West must think dummy's hearts are a threat, and, since he knows I have a doubleton heart, he wouldn't think that unless hearts were 3-3.
For example, give West something like
I can make five by driving the ♦K, since East gets squeezed in the majors. But would West ever continue diamonds with this hand? Unless I have ♥KQ doubleton, I can't set up hearts without losing the lead twice. So why not just persist in clubs, doing what you can to disrupt declarer's communications?
The same thing is true if West has ♥Kxx. Only if I had ♥QJ doubleton would I be able to establish the suit with one loser, so there is no need for desperation. It appears that East has ♥Kxx of hearts, which means I can lead up to my ♥Q and make five. Even if I'm wrong, I'll still make four on this line provided one of my assumptions is correct: either the ♥K is on my right or the suit is 3-3.
I cash the ♣K--♣5--♣9--♣4. So far, so good. If East had shown out, I would have to rethink my conclusions. Admittedly, it's not entirely safe to play another club. If West led a deceptive deuce from a doubleton or from ♣Jxxx or if he simply forgot his lead conventions) and if I get unlucky, I could wind up going down. I might worry about that against human defenders, but I'm not too worried against Jack. He's an honest sort who never forgets his methods.
I play a club to dummy's ace. West plays the ♣6; East, the ♣J. If I cash the last club, I will have to pitch my ♦10, and I'd rather not do that just yet. I'd like to retain the option of establishing a diamond trick. If I lead a heart to my queen and it holds, for example, I can just drive the ♦K to make five and not rely on the heart split. I play the ♥5. East isn't going to allow me to make five that easily. He hops with the king; West follows with the deuce.
East shifts to the ♦7. I rise with the ace, West plays the ♦4, and I pitch dummy's ♠2. This is the position:
The inference I drew on this deal (that an aggressive defense means suits are breaking favorably) and the converse (that a passive defense means suits are breaking unfavorably) come up frequently, often on the opening lead. West certainly knew he had little chance to beat this when he won the ♦Q, so an aggressive defense was called for. But I still don't understand the diamond continuation. A shift to the ♠J seems better.
I don't care for the opening lead either. I can understand not leading a diamond. If you are on lead against 3 NT and have no five-card suit of your own, it is often a good idea to try to find one in partner's hand. But, on this auction, you are more likely to find partner with five spades than with five clubs. Dummy might have an undisclosed club suit (as it did), but it won't have an undisclosed spade suit. I assume Jack chose clubs on the idea that three small is safer than Jxx. But now is not the time to be playing it safe. 3-3 hearts screams for aggressive tactics just as much now as it did at trick three. A spade lead probably won't beat the contract. But it will certainly worry declarer more than the club lead did.
I'm disappointed to discover this board is a push. I thought I did well to make five.
Table 1: +460
Table 2: -460
Score on Board 3: 0 IMPs
Total: +3 IMPs
Plus... it's free!