The 31-year-old was stretchered off with a suspected ligaments tear after colliding with teammate Giuseppe Favalli early in the 5-1 victory at Siena.

Milan confirmed on Monday that their first-choice guardian will have two or three weeks of rehab before undergoing knee surgery, which will probably rule him out for six months.

Backup keeper Dida is likely to take over from Abbiati for the rest of the campaign.

Milan playmaker Kaka also picked up a negligible ankle knock in Sunday's game after being introduced as a substitute.

The Brazil ace's return was quite unfortunate as he was nursing a foot injury over the past month.