Joao Cancelo has undergone successful surgery on his right knee, Juventus have confirmed, and will be out through the end of 2018.
While initial reports suggested Cancelo had avoided serious injury, he instead was forced to undergo a medial selective meniscectomy at the Clinica Sedes Sapientiae in Turin on Friday.
The full-back is expected to be out of action until at least the middle of January.
"Cancelo has a problem with his medial meniscus and will undergo surgery and return after the break," Juventus manager Massimiliano Allegri told reporters on Friday.
The full-back's best chance for returning may be when Serie A resumes on January 19, with Juventus hosting Chievo.
Cancelo has been one of Juve's standout performers since joining from Valencia in a €40 million deal (£36m/$45m), following a loan last season with Inter.
He has made 15 appearances in all competitions for Allegri's side, contributing a pair of assists.
Juventus also may be without the services of Juan Cuadrado for a time, as Allegri confirmed surgery is also a possibility for the attacker.
"With regards to Cuadrado, we need to assess whether or not a small surgery will be needed," Allegri added.
The Serie A leaders, who have won 14 and drawn one of their first 15 league games this term, face city rivals Torino on Saturday. Juventus are currently eight points ahead of second-place Napoli.