Liverpool centre back Daniel Agger has suffered a recurrence of the metatarsal injury which has kept him out of action since September.
The Dane, who was days away from making a first team return, is now not expected to feature for the rest of January and could be out for longer.
"It's not easy to say when he will be back," said Reds manager Rafa Benitez.
"He is going to see different surgeons and then we'll be able to analyse the situation," Benitez added.
The news is a significant setback for Liverpool, as the 23-year-old has been their prefered partner for Jamie Carragher in central defence since he signed from Brondby in January 2006 for £5m.
Agger's absence means Benitez is likely to accelerate the introduction of new defensive signing Martin Skrtel into the team.