The Brazil international spent six years with the 18-time Serie A winners before joining Real Madrid in 2009, where he has enjoyed mixed success.

"It is difficult to speculate on the percentage for Kaka, but as a coach I look at this issue with great interest," Allegri told Rai Sport.

The 45-year-old also spoke about bringing lifelong Milan fan Mario Balotelli to the club, as well as the possibility of making other signings.

"Balotelli is a Manchester City player, and I have not spoken with Roberto Mancini about him, and I think he still has continuing and important qualities," said the former Cagliari coach.

"I do not think there is the need for reinforcements in defence: Mexes' [own-goal in Sunday's Serie A win over Bologna] was a simple accident, which occurred after a positive performance, and we have many good players in that department.

"I think a coach, like a business leader who has people under him, needs to know how to wait patiently for the results of the work."