Jurgen Klopp admits Liverpool remain in the dark over the extent of Fabinho's ankle injury.
The Brazilian was forced off with the problem 19 minutes into the 1-1 Champions League draw at home to Napoli on Wednesday night.
Fabinho needed lengthy treatment on the pitch after being accidentally caught by the falling Napoli forward Hirving Lozano, who had been challenged by Dejan Lovren.
See how Liverpool's draw with Napoli unfolded HERE
After attempting to play on for a few minutes, the midfielder admitted defeat and went straight down the tunnel after being replaced by Gini Wijnaldum.
Fabinho left Anfield with a protective boot on his left foot and is now expected to undergo a scan on Thursday to ascertain the problem, although he was already sidelined for Saturday's Premier League game against Brighton and Hove Albion due to suspension.
“Fabinho has pain, so that's not good,” said Klopp. “He couldn't continue, and he is a hard one.
“I don't want to say what I expect because I hope at the moment it's not that serious.
“We will know more maybe tomorrow or maybe the day after tomorrow. That's it.”
Liverpool will hope Fabinho avoids a lengthy spell on the sidelines as they face a hectic December and New Year period as they continue to challenge on five fronts.
