Honestly think he just needs a big CL goal (or for Argentina) and he'll be fine.
Clearly if he has time to think in a big game he has some sort of mental block, but we are Juve, we will turn him into a killer.
That said, I don't think any of his chances were easy tonight, nothing on the level of his World Cup of Copa America misses.
There were a couple of times though where we were on the break and in Serie A you'd expect him to be darting into the box for a finish and he seemed to hang back. To me that seems like he was slightly nervous.
He just needs a goal or two in the semi, and then he'll score the winner for us in the final.