Staying at Old Trafford means the 18 year old will not get hatfuls of opportunities to start games as he will be behind a queue of Wayne Rooney, Dimitar Berbatov, Michael Owen and Javier Hernandez.
The Italian made his mark two seasons ago when he scored vital goals against Aston Villa and Sunderland to help United lift the title.
Long-term injury prevented the youngster building on his successful start to his United career, now he is fit again but manager Alex Ferguson last season, but Ferguson has issues with his over-confidence.
"He is one we have to keep a close eye on," said Ferguson.
"He has a cocky arrogance about him. He will argue with players in a training session and he will compete for his ego.
"But he's only 18, he's not 19 until October and we keep forgetting that. He is an exceptional talent and he is tough. He does not get bullied in games. He gives a good as he gets.
"There was no chance of us ever letting him go on loan - he stays here. We need to keep an eye on him."