Juventus have lost striker Amauri to the New Year with injury.
Tests confirmed the Brazil-born player has damaged a ligament on his left knee.
Amauri, who recently recovered from a left thigh injury that had kept him out of action for a month, was hurt during Thursday's training session.
A statement from the club read: "Amauri's estimated time for recovery is 40 to 50 days."
Amauri's injury could not have come at a worse time for the Juventus coach Luigi Del Neri, with eight players also unavailable through injury.
Amauri will miss five Serie A games, including Sunday's trip to Genoa as well as the Europa League Group A matches at Lech Poznan and at home to Manchester City.
