Posted 2015-September-01, 09:25
♠ J/10 also.
The auction's over. Stop for a second and think about what you know from it. You hold 13 HCP and the opponents have voluntarily bid 3 NT. They should have somewhere near 26 points to do so. Even if they've pushed a little and hold, say, 24 points, Partner doesn't rate to have more than a K at most.
Even if partner has a trick somewhere, your side will need to set up another trick to defeat 3 NT. The only logical way to do that is set up a long suit trick in one of the hands. With partner holding so few points, it highly unlikely that the trick can be set up and accessed in partner's hand. The most likely place for additional tricks in your hand is the ♠ suit. Since it's a race to set up your long suit tricks before the opponents set up their 9 tricks, it's important to start ♠s immediately.
The normal lead from AJ10xx is either the J (standard leads) or 10 (coded 10/9 leads).