Jurgen Klopp admits he does not know how severe the injury is that was sustained by Dejan Lovren during Liverpool's win over Bournemouth.
The Reds centre-back limped off late on during the 3-0 victory at Anfield and appeared to point to a problem in his groin.
Manager Klopp said: "I didn't see the knock. I would love if it would be because of a knock, but if it's because of a strain, tear or whatever, I have no clue.
"He felt something, but I didn't speak to him afterwards. I only saw that he was limping so we made a change because we could. We had a centre-half on the bench.
"Hopefully it's not too serious, but I cannot say more about that now."
The 28-year-old Lovren has made 36 appearances for Liverpool this season and scored in the reverse fixture at Bournemouth in December.
Liverpool's most recent win moved them to 70 points from 34 games, having played twice more than second-placed Manchester United and once more than Tottenham and Manchester City.