Juventus midfielder Sami Khedira will be unavailable for three months after he underwent surgery on his left knee.
The club released a statement confirming the 32-year-old travelled to Augsburg, Germany, to undergo an "arthroscopic cleaning," and he isn't likely to return until February or March.
Sky Sports said Khedira underwent a similar operation on his right knee in April, a procedure that sidelined him for 10 weeks.
Khedira has established himself as a regular under Maurizio Sarri and made 17 appearances in all competitions to already match his total from an injury-hit 2018-19 campaign.
Football writer Carlo Garganese recently highlighted the Juventus midfield as a weak point for Sarri and a reason why the team may miss out on this season's Serie A title:
Sunday's fixture was the first time Khedira has been omitted from a matchday squad this season, an indicator as to how important he's become to Sarri's plans since he arrived in Turin.
The Germany international has started 13 times as the primary anchor in a midfield three, mostly alongside Miralem Pjanic and Blaise Matuidi.
Broadcaster Deji Faremi and blogger Marco Messina each expressed concern earlier this season regarding how that midfield trio would cope:
Khedira's absence could provide a lifeline for compatriot Emre Can, who has been an outcast in Turin this season.
Can made just his second league start of the campaign in the draw against Sassuolo; Juventus also drew 1-1 against Lecce in October when Can made his only other Serie A start of the term so far.
The former Liverpool man has made only six appearances in all competitions under Sarri, but his involvement promises to increase over the coming months, at least.
Rodrigo Bentancur and Aaron Ramsey could also benefit from Khedira's time out of the squad.
Khedira—who has a contract with Juventus that runs until 2021 (with the option of an additional year)—will return to the squad in early 2020 hoping the Bianconeri's trophy pursuits don't falter in his absence.