The Italian looked set to be the next big star at United when he burst onto the scene, scoring a great goal in injury time against Aston Villa in 2009. After that he just seemed to fade into the distance with many fans saying that he was just not up to the job.
The striker said: "When I had my debut it was great but then I didn't have the chance to play every game. When I got on the pitch, I tried to do my best and it wasn't easy.
"I was only 17 then and I knew I could not play in every game. It has been difficult, but I don't want to think about the past.
"Now I am here and I want to do very well here. I had a tough time. I didn't get on the pitch many times but it is a good experience. You have everything to learn about bad things as well so I take it as an experience and of course I need to step up to become a real player. Now I am young and I need to step up to become a big player. That is what I am looking for."