In an online Seniors (yes...sigh) event, I held this hand:

AJ
K10976
AK6
876.

Of course I opened 1NT (almost every teacher/writer today is on board with opening 15-17 balanced this way, even with a 5-card major). Partner raised to 3NT and the 3 was led.

K762 Q82 J32 A42

AJ K10976 AK6 876

In notrump, we count top tricks. This lead provides 3 in spades to go with AK-A in the minors. That makes 6, and 3 heart tricks will get the total to 9. Even with a misguess for the J, there are still decent chances. Aside from clubs, everything is well stopped. Even with a heart misguess, the stoppers will hold up unless there is a club switch and the player with the long clubs has a heart entry.

There is no sure thing here, as we can't know where the J is. Let's say you play low from dummy and win East's 10 with the jack. You should play hearts next, but what about the 2-way guess for the J? Should you lead low to the Q, or start out by finessing against West for the J?

In a "vacuum" (no considerations outside the heart suit), low to the queen is best. You wouldn't want to lose on the first round to East's singleton jack. But, we are not in a vacuum. I decided to lead the 10 at trick 2 and when West played low, I let it run.

Why? Let's say it loses to the jack. East is likely to return partner's suit (a club switch might be tough to find). If a spade is returned, I am home-free with 9 tricks. I'd win the spade return and play more hearts; 9 easy tricks. Meanwhile, if the finesse wins, life is easy (just repeat the finesse).

Why is this better than playing hearts the other way? It is a matter of entries. Say you play a heart to the queen at trick 2. Whether or not it wins, there are entry problems looming. Say the Q wins and then you play a heart to the ten and jack. Now, if the defense shifts to clubs, you can't untangle the spades. There will be no entry to the 9th trick, dummy's K.

By keeping the Q8 (running the 10 at trick 2), you keep a sure dummy entry to untangle all 9 of your tricks. If the 10 loses to the jack, you claim on a spade return, but also might survive a club return. This is the Real Deal:

Vul:South Dlr: Both	K762 Q82 J32 A42
Q953 AJ4 Q87 QJ9		1084 53 10954 K1053
	AJ K10976 AK6 876

When the 10 won at trick 2, all was good. Notice that a heart to the queen and then a losing finesse will lead to defeat (assuming West finds the club switch). Often a 2-way guess hinges on safe/danger hand, but in this case it was a matter of entries.