You and your partner did well to avoid 3NT, which would have been down on a heart lead. Against your spade game, West leads a third-highest ♥5, East playing the jack. This looks challenging. How will you get to 10 tricks on this deal?
At trick one, declarer saw that if trumps were 3-3 he could win the first trick with the ace, ruff a heart and draw trumps in three rounds and then play on diamonds: he would lose only a heart and a diamond. However, declarer then asked himself, “What if West started with four trumps and a doubleton diamond?”
In that case, if, after ruffing a heart, declarer played on diamonds before drawing trumps, East would win the second diamond and play a third diamond for West to ruff. West would then exit with the *C*J, thereby ensuring the contract would fail. On the other hand, if declarer drew trumps before playing on diamonds then, on the actual layout, East would win the ♦A and cash three heart tricks.
Declarer, therefore, let East hold the first trick. East then then shifted to a trump. As entries to hand were limited to the trump suit, declarer was careful to win this in hand with the ♠10 so that he could ruff the ♥8 in dummy with the ♠Q. Declarer continued by overtaking the ♠K with the ace so that he could draw West’s remaining trumps with his 10 and 8.
Declarer’s next move was to play a diamond to dummy’s 10. East allowed this to hold, so declarer continued with the ♦K. East paused to consider the situation. It was obvious that declarer had the ♥A. East saw the if he let the ♦K hold he would be endplayed on the third round of diamonds and forced to lead a heart to declarer’s ace or a club into dummy’s tenace, gifting declarer an overtrick. So East took the trick with the ♦A and exited with the ♦9 making sure that he would score the ♣K as the defense’s third trick, but declarer still had his contract. The full deal: