Liverpool manager Jurgen Klopp has confirmed Joel Matip will miss the crucial Champions League game against Spartak Moscow on Wednesday through injury and he is a doubt to face Everton in the Merseyside derby on Sunday.
Matip was injured during the Premier League win against Stoke last week and missed the 5-1 win at Brighton on Saturday.
Klopp has confirmed the 26-year-old will also be absent for a game that will decide if Liverpool make it through to the Champions League knockout stages.
"He has hurt his muscle. I don't know how long exactly he'll be out, but he's definitely not playing Wednesday," Klopp told Liverpool's official website.
"A month? No, I don't think so. But as always, it's possible. We have to wait.
"But it's possible that it will be shorter. We will see."
Georginio Wijnaldum and Emre Can were both deployed in defence against Brighton and Klopp said he was impressed with their performances.
He said: "Emre needs to do that, like Gini can do that. They have to do it, we don't have anybody else.
"I enjoyed it. It was like 'wow, interesting.' We had 20 minutes in training and then we spoke for a little bit in the team meeting before the game again about it.
"But it's not long. It was clear it wouldn't be perfect, but the boys were ready to cope with the difficulties of the new system. They did really well."