Mainan had injured his left wrist, while he was saving a penalty kick by Egyptian Mohamed Salah during the Liverpool match and AC Milan in the Champions League.
Mainan managed to block Salah’s strong penalty, but he paid the price dearly, as he was replaced during the meeting due to wrist pain, which later turned out to be a torn wrist ligament.
“Milan can confirm that Mike Mainan underwent an endoscopic examination today, which revealed a ligament injury to his left wrist, which has been treated,” Milan said on their website.
“The surgery worked perfectly. He will rest for six weeks before starting rehabilitation. He is expected to be out of action for ten weeks.”
Mainan has starred since joining Milan from Lille last May, in a 5-year contract, and has played all Milan matches in the Italian League and the Champions League.
His absence is a blow to coach Stefano Pioli, as his goalkeeper will miss several important matches, including the remaining four for Milan in the group stage of the Champions League, as well as the matches between Roma and Inter Milan in the league.
It is unlikely that Mainan will return to the stadiums again before the winter break in the Italian League next January.