The Brazil midfielder - who played for the Rossoneri between 2003 to 2009 - returned to San Siro on a free transfer last week after four years with Real Madrid.
He played 45 minutes in a 4-0 friendly win against Chiasso of Switzerland on Saturday, wearing the captain's armband, and showed enough to suggest he could be a key player for Allegri this season.
"Kaka is a great player. He has quality and he is a CHAMPION, very experienced." - Says Allegri for Sky Sports.
"I must do well to get the best out of him and help him reach peak fitness. You cannot expect a player, even one of his level, to be ready straight away.
"Kaka is a lovely guy who is eager to work hard, which he proved already in training."
Kaka is expected to officialy re-debut next week-end.
