Mati Fernandez has a lesion to his right thigh muscle and the Milan midfielder will be out for at least two weeks.
He sustained the injury during international duty with Chile this week.
Flying back to Italy, Mati Fernandez underwent tests today.
A statement was released confirming there is a lesion to the muscle in his right thigh, but the extent of the damage was not revealed.
The note merely states his condition will be evaluated again in two weeks.
This seems to fit with the predictions from some media sources that the former Fiorentina man would be out for a month.
Fernandez completed his transfer on deadline day, but is yet to make his debut in a Rossoneri jersey.