Mane suffered the injury in a challenge with Leighton Baines, having earlier scored the opening goal
Mane, 24, was taken off after colliding with Leighton Baines in Saturday’s 3-1 home victory over Everton.
Manager Jurgen Klopp said he was “pretty sure” Mane needed surgery, leaving it “pretty much impossible for him to play again this season”.
The £34m signing from Southampton has started all but five of Liverpool’s league games this campaign.
Of those, three were drawn and two were lost. The Reds are third in the Premier League table with seven games left.
Klopp also said Adam Lallana was “much better but is not in training” as the midfielder continues his recovery from a thigh injury suffered on England duty in March.
Captain Jordan Henderson, who has been out since February, is “in a good way, but I don’t know when he can be part of training again”, the German added.
Sadio Mane posted a photo of his knee on Instagram on Thursday
