Spanish media claim Ricky Kaka will be out for a month with a muscular injury, but Milan have not confirmed any setback.
The Brazilian made his ‘debut’ for the Rossoneri in Saturday night’s 2-2 draw with Torino  and played for 70 minutes.
There are rumours in the Spanish Press that Kaka has picked up a thigh strain that could rule him out for up to four weeks.
It would be a heavy blow if true, as Milan already have a huge injury crisis on their hands going into the Champions League against Celtic and Serie A with Napoli next weekend.
Riccardo Montolivo suffered a thigh strain against Torino and Andrea Poli was left with a heavy bruise to his leg.
They joined the already sidelined Stephan El Shaarawy, Mattia De Sciglio, Giampaolo Pazzini, Mathias Silvestre, Daniele Bonera and Ignazio Abate.