Liverpool left-back Fabio Aurelio has been sidelined for up to a month as a result of the hamstring injury sustained in Sunday's 3-1 victory over Manchester United.
Liverpool head of sports medicine and sports science Dr Peter Brukner said via the club's official website that the Brazilian could be out for up to four weeks.
"He's got a significant hamstring injury," Brukner said. "Unfortunately his body lets him down. He always play well when he's fit. We've been managing him carefully because he's not been playing twice in a week, but this just came out of the blue.
"He had a minor adductor strain a few weeks before that. We rehabilitated him and he trained all week with no problems at all.
"He'll be out for a month so that's a blow. It's a partial tear. It's what we call a secondary degree hamstring. It's similar to Martin Kelly's and these are three or four week injuries."
In other injury news, Brukner revealed Denmark defender Daniel Agger is unlikely to be fit for Thursday's Europa League clash with Portuguese outfit Braga.
"Daniel had a nasty kick on a joint to the side of his knee. It's an unusual spot to get an injury. They take time and he's a bit of a slow healer. He's still not 100% so we'll have to see if he's fit for the game this week. But it's more likely to be the following week."
There was also an update on young English midfielder Jonjo Shelvey, with Brukner saying the Anfield club are satisfied the 19-year-old's recovery from a knee injury is on track.
"We are also happy with Jonjo's progress. He's working hard to strengthen the tendon that's been damaged."