Balotelli, 17, struck twice in Inter's 3-2 Coppa Italia victory over Juventus this week and has been dubbed 'Italy's Alexandre Pato'.
His former boss at Serie C2 Lumezzane, Michele Cavalli told Radio R101: "I was well aware that he would achieve great things and anyone who knows Mario knows that he has such great ambition to play at the highest level.
"But I have to say that he has a difficult character and that has to be taken into account.
"I won't deny that we frequently had arguments and he also had disagreements with teammates."
He added: "He is blessed with the mixture of great agility and co-ordination and he can respond to things that others can't.
"My advice to Roberto Mancini? I would only say that he should keep playing him because Mario is a unique talent.
"The only difference between Balotelli and Pato is the investment. Inter were lucky to find such a player for a far smaller sum. Mario has a lot of room for improvement, but he could become better than Pato."