The Atletico Madrid striker has joined Juve on an initial loan.
“Being back here is great," he said at his official unveiling.
“I'm now a more experienced person and player. This is the chance of a lifetime.
“Seeing Pirlo as a coach has been great. I saw it coming because he was made to be one. Juve need him and I'm happy to be here with him.
“After the first two training sessions, I was already impressed with how he managed the group. He knows how to get us to play well with the ball.
“I'm sure we'll do well. I'm ready to play and do whatever the coach asks of me. I want to win and I'd like to score 35 goals.
“I've always said that my dream was to play for Atletico Madrid, but they were banking on me here when I was a still a young lad, so I'm very grateful.
“I'm at the right place at the right time. The best memory of when I was here is my wife, in addition to the trophies I won, which are unforgettable."