Dejan Lovren had to be substituted after five minutes of Liverpool's FA Cup third-round tie at Wolves after picking up a hamstring injury.
Manager Jurgen Klopp confirmed after the match that Lovren had an issue with his hamstring, and now the 29-year-old joins defenders Joe Gomez and Joel Matip on the treatment table.
"Hamstring is what I heard, without any signs of anything before," said Klopp in his post-match press conference.
"I asked everybody [before the match], no signs [of injury] so that's a decision you have to make. I'm not sure what you would have said if immediately we started with Fabinho and Ki-Jana Hoever.
"Probably a few very smart people would tell me I don't respect the competition or whatever."
Croatia international Lovren came back injured from the World Cup last summer and his place was taken by Gomez.
But he regained his position in the side following Gomez's injury against Burnley in early December.
Lovren was replaced by 16-year-old Ki-Jana Hoever, who became the youngest player to appear for Liverpool in an FA Cup tie. He is also the third youngest Liverpool player across all competitions.
Hoever, who was born in 2002, came on to partner Fabinho at centre back at Molineux.
Speaking about the full-back before the match, Liverpool manager Jurgen Klopp said: "It is just a joy to watch him. He is an incredible, confident young fella and is really a good player on top of that."
The game was goalless at the time of Lovren's injury but Raul Jiminez put Wolves ahead after 38 minutes.