Juventus captain Giorgio Chiellini will have surgery for a torn right ACL he suffered during training on Friday, the club have announced.
No timetable has been given for a return to action for the 35-year-old defender, whose contract expires next summer.
"During today's training, the captain reported distortion of his right knee and a lesion of the anterior cruciate ligament," Juventus said in a statement.
"The diagnostic tests performed at JMedical showed the lesion of the anterior cruciate ligament.
"It will be necessary to have surgery in the coming days."
The Italy international has made 507 appearances for the Bianconeri since joining from Fiorentina in 2005 and has been capped 103 times for his country.