Liverpool defender Joel Matip is set to miss six weeks with a broken collarbone suffered in the Reds' Champions League group stage victory over Napoli on Tuesday.
Matip was taken to hospital immediately following the 1-0 win for tests after sustaining the injury right as referee Damir Skomina blew the whistle for full-time.
The centre-back will require surgery on his shoulder in what is another defensive injury blow to Liverpool manager Jurgen Klopp.
"Matip was taken to hospital following the fixture and further assessment deemed an operation is required," a statement on Liverpool's website said.
"Early indications suggest the centre-back is facing a spell of up to six weeks out of action, though that is dependent on how Matip responds to his treatment and rehabilitation programmes."
Joe Gomez is also not expected to return until the new year after fracturing his leg at Burnley last week, while Dejan Lovren has only just returned from a concussion.
However, sources have told ESPN FC that Liverpool believe summer signing Fabinho is capable of operating as a central defender.
At right-back, Liverpool are continuing to assess Trent Alexander-Arnold's foot injury that forced him off in the 90th minute against Napoli ahead of Sunday's meeting with Manchester United.