Liverpool have said defender Joe Gomez will undergo more surgery to help his recovery from a lower leg fracture.
Gomez has been absent since December and was initially expected to be sidelined for six weeks.
However, the 21-year-old's recovery has been more complicated than thought and he will have further surgery to aid his rehabilitation.
"The club's medical staff believe he will benefit from a further procedure to enable a more complete recovery," a statement on Liverpool's website said.
"No timescale will be placed on an expected return date for Gomez, though it's likely he will feature again this season."
Gomez had made 18 appearances this season before suffering the injury in a challenge with Burnley defender Ben Mee on Dec. 5..
"It's a blow for the boy and for us, because prior to the injury he was in such fantastic shape," manager Jurgen Klopp said.
"But he is too valuable to take any risk with, both for our present and future, so we get this procedure done and he comes back when he's ready.
"His attitude during this rehab has been outstanding, but it just hasn't healed as we'd have liked so we will make this intervention and then he will come back."
Liverpool are also hopeful that right-back Trent Alexander-Arnold will return to full training this week after knee ligament damage.
The Premier League leaders travel to West Ham on Monday with a two-point advantage over Manchester City at the top of the Premier League.