Juventus vice-captain Giorgio Chiellini is facing three months on the sidelines after tearing his calf in training.
Bianconeri head coach Antonio Conte had admitted the Serie A leaders were likely to miss the 28-year-old defender's services for the foreseeable future after he pulled up in training, and medical tests have confirmed the Juve boss' suspicions.
A statement on Juventus' official website read: "This morning Giorgio Chiellini underwent an ultrasound scan at Turin's Istituto di Medicina dello Sport medical centre.
"The scan revealed a tear in the defender's right calf. He will begin his rehabilitation programme, defined by the club's medical staff, over the course of the next few days."
Conte's men, who lead Serie A by seven points, face Cagliari on Friday night before a two-week winter break begins.
He told the club's official website: "It's a shame Chiellini's injured, he's a player everyone would like to have, for what he offers both on and off the field of play.
"He's one of our leaders. But I'm convinced he'll come back stronger than before, looking to recover as soon as possible with the help of the club's medical staff."