Borussia Dortmund midfielder Axel Witsel was hospitalised at the weekend after falling at home.
The Belgium international, 30, left the hospital on Monday, but will not return to action until 2020.
"Witsel sadly will be out for the rest of this year," Dortmund coach Lucien Favre told a news conference ahead of Tuesday's Champions League match against Slavia Prague.
"But there is one positive thing: He's already back home. We can't change it now. It's a shame for him, a shame for us. He's one of the most important players for us."
On Saturday afternoon, Dortmund -- with Witsel in midfield -- beat Fortuna Dusseldorf 5-0 at home in the Bundesliga. The following morning, Favre was informed about his player's fall.
"I was told about this yesterday morning," Favre said on Monday. "We could not speak to him. He was in hospital."
🤕 @axelwitsel28 hat sich nach einem Sturz eine Gesichtsverletzung zugezogen und fällt für den Rest des Jahres aus. Er wurde im Anschluss an den häuslichen Unfall erfolgreich operiert und konnte das Krankenhaus schon wieder verlassen.
— Borussia Dortmund (@BVB) December 9, 2019
Gute Besserung, Axel! 🙏 pic.twitter.com/unveAlEFjp
Dortmund media director Sascha Fligge said the midfielder "fell awkwardly at home," and a club statement on Twitter read: "Axel Witsel sustained a facial injury and will be out for the remainder of the year. He underwent surgery following the accident at home and has since left the hospital."
ESPN FC has reached out to German authorities for further information.
The midfielder has made 64 competitive appearances for Dortmund since returning to Europe from China in 2018.
He will miss the upcoming clash with Prague, as well as games against FSV Mainz, RB Leipzig and TSG Hoffenheim.