The Frenchman likened the young Italian to current stars Craig Bellamy and Carlos Tevez, two players who are known for their feisty demeanour.
"He is a really exciting player. There is no doubt about his qualities as a football player - he is young and talented and that is really good for the future as well," said Vieira.
"He is similar to Craig and Carlos. Players have their own temperament, and their own way of behaving, but what is important is that everything a player has to do, he does it for the football club.
"He hasn't signed for us yet but he is a young talented player who enjoys his game.
"He is a good goalscorer who makes scoring goals look easy. He doesn't need five chances to score a goal."