Juventus defender Giorgio Chiellini has been ruled out for around six months after having surgery on a damaged anterior cruciate ligament.
The experienced centre-back injured the ligament in his right knee during a training session last Friday.
The Serie A champions said in a statement on Tuesday: "This afternoon, Giorgio Chiellini underwent surgery to reconstruct the anterior cruciate ligament of the right knee.
"The intervention, performed at the Hochrum clinic in Innsbruck by Professor Christian Fink in the presence of the Juventus Club Doctor, Dr. Tzouroudis, was perfectly successful.
"The expected recovery time is around six months."
Chiellini is likely to return in March, meaning he could be fit for the Champions League quarter-finals should, Juve reach that stage.
The 35-year-old has made 384 league appearances since joining Juve from Roma in 2005.
An eight-time Serie A champion, he was a key part of the defence under former coach Massimiliano Allegri, although muscle problems restricted him to just 22 league starts last season.
In April, the Italy international told DAZN he expected to play "for another year or two" and then take up a backroom role at Allianz Stadium.