Pato joined the Italian side from Internacional for £10m.
“He has all the quality of a champion, but he must understand that in Italian football if you want to last for 10 years you’ve got to give 100 per cent every single day,” said Milan director Leonardo.
“He has to run, fight, sweat in training and listen carefully to the advice of Coach and teammates.”
He added: “He has no physical problems, nor psychological ones. He is happy within the squad and working hard. The directors are very close to him, both in terms of his sporting career and his private life.
“Pato is a valuable member of the club and we have absolute faith in him.”
