Trick one was 6♠, 2, J, K
Trick 2: 2♥, 7♥, A♥, 9♥
Trick 3: K♥, 8♦, 4♥, J♥ (standard signals)
Trick 4: 3♥, 2♦, 5♥, Q♥
I underled my A because I had no lead that struck me as "obvious" and did not expect either declarer or dummy to have a singleton spade. Since partner played the Jack, I decided that he couldn't have the Ten, and that it could not be right to underlead my Ace again.
Sadly, that was probably the only way to beat the hand. Partner had played the Jack from JT doubleton of spades. The whole hand.
Furthermore on the tenth trick of the hand partner was endplayed. On the trick I was able to overtake, but it would have promoted a trick for declarer just as much as the endplay did. Is there a name for such an unfortunate situation?