Liverpool defender Dejan Lovren suffered a hamstring injury during Monday's 2-1 defeat to Wolves in the third round of the FA Cup, manager Jurgen Klopp has confirmed.
Lovren was one of just two players retained in Klopp's starting XI from last Thursday's defeat to Premier League title rivals Manchester City but he pulled up during the early stages at Molineux.
It meant 16-year-old Dutch defender Ki-Jana Hoever was introduced, becoming Liverpool's youngster ever FA Cup player.
Hoever played alongside defensive midfielder Fabinho at the heart of Klopp's defence as goals from Raul Jimenez and Ruben Neves saw Wolves through, and the youngster's countryman Virgil van Dijk is now the Reds' only fit senior centre-back as Joe Gomez (broken leg) and Joel Matip (fractured collarbone) remain in rehabilitation.
Speaking at a post-match news conference, Klopp insisted Lovren's selection had not been a risk and rebuked any suggestions his much-changed side suggested a lack of respect for the FA Cup.
"[It is his] hamstring, is what I heard - without any signs before. I asked everybody, no signs, nothing, just out of the blue, so that's the decision you have to make.
"I am not sure what you all would have said if immediately from the beginning if our centre-half situation was Fabinho and Ki-Jana; then probably a few very smart people would tell me that I don't respect the competition or whatever.
"So, we tried to do all the things [we could]. Of course, on the other hand it doesn't make sense to bring in a 16-year-old boy from the start. You don't bring him, you wait until he is completely ready, but he did well. He came on and did well.
"That's how it sometimes starts - when you are really needed then it is only about if you are good enough and not how old you are. He did well, so that was all okay."
Klopp said he was unsure at this stage over the amount of time Lovren was facing on the sidelines, while at the weekend he told reporters Gomez and Matip were progressing but a few days away from returning to training.
"[Joe is] getting better, it's getting better, but he is not yet involved," he said.
"Joel is maybe a bit closer, I'm not sure, but hopefully he moves completely normal. We have to see how the bone healing is, that's always how it is when something [has] broken, but from his movements it looks nearly normal.
"But there are still a few days to go until we can have them in team training, until [Joel] is ready for contact, which for a centre-half is pretty important. Until then we will make all the fitness work.
"The good thing is Joel can do all the fitness work already since a week or so ago, so that means when he will be back he will be 100 per cent fit. Then he has to get rhythm and everything will be fine."