Newcastle striker Alan Shearer fears his career is over.
Shearer has netted 206 goals in his Newcastle career
Shearer, scheduled to play three more games before retiring at the end of the season, limped off in the 71st minute of Monday's 4-1 win over Sunderland.
"It doesn't look good. They think there might be a tear in the medial ligament, and if that is the case then that'll be it for me I'm afraid."
Shearer, who netted his 206th goal for the Magpies before going off, will have a scan on Thursday.
That should determine whether he can play any part in any of those three remaining matches.
Shearer's final game was set up to be the home match against Chelsea on Sunday 7 May.
The former England captain said he did not want to finish his career early.
"I wanted to go the full distance, yes, but if I have to finish, then it's not a bad way to finish, coming to your local enemies and scoring a goal that's helped us get a 4-1 win," he said.
Shearer's 206 Newcastle goals have come from 404 appearances since he joined in summer 1996.
He netted a total of 379 goals in 733 appearances in a career encompassing spells at Southampton, Blackburn and Newcastle.
He also scored 30 goals in 63 appearances for England.