With the help of new-minor forcing (your 2♦ bid), you find your eight-card spade fit and bid game in that suit. West leads the ♦J and you pause to take stock. Do you see a path to 10 tricks?
West led the jack of diamonds and declarer paused to assess his options. His first observation was that he probably needed trumps to be 3-2. Even if they broke favorably and hearts were 4-3, he would still have only nine tricks: four trumps, two hearts, a heart ruff and the minor-suit aces. It was then that he saw the way forward: he needed to make all five of his trumps, his four side-suit winners and a heart ruff to bring his trick total to 10.
At trick two, declarer played a club to the ace, then ruffed a club. After cashing dummy’s ♠A and ♠K, trumps, declarer ruffed another club. Then came the riskiest part of the plan: he cashed the top hearts and ruffed a heart. When the ♠5 held up, South had nine tricks – just one short of the contract. So he led the ♣J from dummy, thereby neutralizing East’s ♠J, the master trump.
If East had ruffed high, declarer would have thrown a heart from hand and would eventually have scored his remaining trump for his 10th trick. In practice, East discarded a diamond, thereby allowing declarer to score his 10th trick by ruffing the ♣J. The full deal: