Milan may have announced the signing of Alberto Aquilani today, but they've lost Mathieu Flamini for the next five months.
The Frenchman picked up a right knee injury in the Trofeo Berlusconi match against Juventus last weekend.
Tests have now confirmed that the former Arsenal man has damaged ligaments and he'll be out of action until 2012.
The San Siro giants had insisted that their transfer market campaign had come to a close with the acquisition of Aquilani from Liverpool.
However, the club could now look to replace Flamini just days after links emerged with Cesena's Marco Parolo.