Source: Daily Bulletin of the San Francisco Nationals.
Many pairs will have reached 7
on this deal from the second qualifying session of the Victor Mitchell Open BAM (hands rotated).
Deep Finesse assures us that 7 can be made, but that is strictly double dummy and complete fantasy in real life. At the table, West will lead the 
Q to dummy’s ace and declarer plays a heart to the king. When the 9 appears, declarer has a two-way finesse position for jack-to-four with either defender. Is it a guess, or is it correct to play one defender rather than the other for the trump length?
Actually, the answer varies according to the competence of the defenders. Against inexperienced players, the 9 rates to be a true card, and declarer should play to the A next to cater to East’s having the heart length. But against experienced defenders, declarer should play the Q next, catering to West’s holding the length.
When West holds J 9 x x, he has to play the 9 on the first round to give declarer a losing option. East, of course, has no choice but to play his singleton. When West holds the bare 9, East could have played any one of his three equal low hearts on the first round, and the assumption is that he will sometimes play each of those cards. As in all restricted choice situations, the rule is to assume that the opposition played the way that they were forced to do, rather than that a defender exercised a choice of plays.
Having got the trumps wrong by following this reasoning, declarer will be pleased to discover that the spades do not come in so that he could not make 13 tricks however he had played the trumps. Maybe he will get a half on the board after all. Duly consoled myself with this thought after going down in the grand slam, only to find that the contract at the other table was 4. Ugh!
So, how do you make 7 on the lead of the Q? If you can see all the cards, you win the A, play a heart to your king, noting the fall of the 9. You then play the 
J and a club to the ace, followed by the 10 or 8. Now a diamond ruff with the 3, is followed by the Q, a club to the king. The A picks up the last trump, and you discard one of your low spades on that card and another on the fourth round of clubs.
It’s an easy game