Jurgen Klopp has confirmed Fabinho is set for a scan on a hamstring injury after he was withdrawn against FC Midtjylland on Tuesday evening.
The versatile midfielder was injured in the first half of the 2-0 win over the Danes and was replaced by Rhys Williams at centre-back where he has deputised in the absence of Virgil van Dijk and Joel Matip.
The 19-year-old turned in an assured display alongside Joe Gomez but any lengthy absence for Fabinho would be a huge blow for Klopp and Liverpool.
At a time when Van Dijk is likely to miss the season with an ACL injury and Matip is struggling to prove his long-term fitness, Klopp can ill afford to lose the Brazilian for a significant period.
Klopp said: “We lose pretty much one of the last men standing at the back, you bring on a 19-year-old kid and no-one knows how that’s going to work out.
“But Rhys was not our problem tonight, he did really well. He was commanding, he was chatting and all this kind of stuff, so he played a really good game.
“We have to wait after a scan obviously. You know in these times when someone has a muscle problem and it’s pretty rare the doctor calls me the next morning and says it’s a false alarm, all fine and he can go again.
“So now it’s only about how long, that’s all. Now a week means three games, 10 days means four, 14 days means seven games and all this kind of things, so that’s how it is.
“Yes, it’s absolutely not cool but that it is the situation.”
Klopp added: “It’s exactly the last thing we needed. I know he felt a hamstring, and that’s not good.
“He said he could have played on but no sprints, which doesn’t help. We will see, we will know more after a scan.”
Jordan Henderson was also withdrawn at half time for Gini Wijnaldum but Klopp said the Reds skipper is not injured.
“Hendo said at half time, he wanted to play on,” Klopp added.
*Who was your MOTM tonight? Cast your vote in our quick poll.
“But before the game I decided that we have to share 45 and 45. Hendo said ‘no, boss, I can go on.’
“In these moments you have to be strong because I didn’t want to lose him actually.”
The Reds return to action on Saturday evening when they host West Ham United in the Premier League before another Champions League tie at Atalanta next week.