It was reported on Thursday that Massimo Oddo had picked up a gluteal strain during Milan's Champions League tie with Olympique de Marseille, and that he was rated as doubtful for the club's weekend trip to Catania.
However, further scans have revealed the full extent of the problem, and the 33-year-old is highly unlikely to feature again this year.
Milannews.it report that Oddo has torn a muscle in his left thigh, which will rule him out for at least two months.
It is a blow for Rossoneri coach Leonardo. The former Lazio right-back has featured regularly for the club this season after an unsuccessful loan spell with Bayern Munich last term.
Ignazio Abate is likely to deputise at for Milan on Sunday, and it is likely that he will continue to do so until the return of either Oddo or Marek Jankulovski.
The Czech defender has been struggling with an ankle injury recently, but was back in light training on Thursday. His return would allow Gianluca Zambrotta to return to a more familiar role at right-back.
Anthony Wright, Goal.com