AC Milan have announced that Oguchi Onyewu will be out for about six months after the defender underwent surgery on a knee tendon injury.
The American picked up the serious problem while on international duty against Costa Rica last Wednesday.
After talks with Milan's doctors, the American team's medical staff decided to put him under the surgeon's knife.
The Italian club have since announced that the surgery has proved successful but he will be out for six months.
The 27-year-old only joined the Serie A giants in the summer and Milan general manager Adriano Galliani has previously stated the club will seek damages from the American Football Federation.