Liverpool forward Philippe Coutinho had a scan on his ankle injury on Monday amid fears he could be sidelined until the middle of January.
Coutinho, 24, was taken off on a stretcher after colliding with Didier Ndong of Sunderland during the first half of Saturday's 2-0 win at Anfield.
Though the full results of the scan are yet to be revealed, the likelihood is the Brazilian has ligament damage.
That usually means a player is sidelined for five or six weeks.
It means Coutinho, one of Jurgen Klopp's most influential players as the Reds have moved into second place in the Premier League, looks certain to miss key games.
Liverpool face Everton in the Merseyside derby at Goodison Park on 19 December, and meet Manchester City at Anfield on New Year's Eve.
Coutinho would miss both games if ligament damage is confirmed.
He was at Liverpool's Melwood training headquarters on Sunday, leaving on crutches with his right ankle in a protective boot before having his scan 24 hours later.
Klopp will also be without £34m summer signing Sadio Mane in January as the striker will be on Africa Cup of Nations duty with Senegal.
The German is unlikely to risk Coutinho's countryman Roberto Firmino in Tuesday's EFL Cup quarter-final against Leeds United at Anfield after he took a kick on the calf against Sunderland.
Daniel Sturridge, who missed that game after reporting tightness in his calf, will be sidelined again.
Adam Lallana, who has missed Liverpool's past two Premier League games after injuring his draw during England's 2-2 draw with Spain at Wembley, continues to make good progress. He is in training again under the guidance of Liverpool's fitness coaches but will not be considered for the match Leeds.