Liverpool defender Glen Johnson is facing at least a month on the sidelines and is still waiting to learn the full extent of his knee injury.
The England right-back suffered a tear in his medial ligament during the closing stages of the 1-0 victory over Aston Villa on Tuesday night.
Johnson will not feature again for the Reds until February at the earliest and Rafa Benitez has conceded that he is not certain when the full-back will be able to return.
The former West Ham, Chelsea and Portsmouth defender must seek the opinion of a further specialist before an exact timescale can be put on his recovery.
Benitez told the club's official website: "Johnson has a problem, so he'll see a specialist and then we'll talk but we know he'll be out for at least one month.
"But we are waiting for another opinion and then we'll know how long."
Benitez believes winger Albert Riera could return in the coming days from his hamstring problem, but fringe players Martin Kelly and Nabil El Zhar need a longer recovery period.
"Kelly and Nabil still need maybe one or two weeks," added the Spaniard. "Riera will start training tomorrow, so hopefully in the next week he can be available."