Liverpool manager Jurgen Klopp says he cannot set a return date for Daniel Sturridge who suffered a hamstring injury during Sunday's defeat by Newcastle.
The 26-year-old has been struggling for fitness this season but recently looked set to become a regular in the German's side.
But having just returned to action after knee and foot problems, the Englishman is now expected to spend more weeks on the sidelines.
"It's a hamstring and it's not easy to say when he can be back for us," Klopp revealed.
"There are two different things we have to look at – the one thing is the injury and the other is how we can bring him into a shape that is not so intensive for him, so he needs to train.
"The good thing with the muscle injury is that early [on] he can start to run and to train - not football but all the other things he needs. If you look at his history in the last months, and maybe the last year, it's not a long time he's been able to train.
"With all the games [we have], we have to find the specific point when it's possible to bring him [on] for minutes and what makes most sense for his general shape.
"I can't say at this moment what we will do exactly, but we'll have to look at it.
"The injury is not that serious. The last time he trained, he got 60 minutes at Southampton, which was quite good, and then another 30 at Newcastle, which was not that good because in one of the first moments when he had a shot at goal, he felt something in the muscle.
"It's not that serious, but it's not possible to play. Now we have to build up his resistance. It is like it is. We have to help him be more resistant for all the games we have."
