Liverpool centre-back Daniel Agger suffered a broken rib during Sunday's loss to Tottenham Hotspur.
The Danish defender sustained the injury in the first half at White Hart Lane and was replaced by Sebastian Coates.
"Daniel has got a fractured rib, so he's struggling a bit," manager Kenny Dalglish told the club's official website.
The injury is likely to keep the 26-year-old out of action for a month.