Liverpool captain Jordan Henderson will be sidelined for at least five weeks.
Henderson pulled up during the first half of the Premier League champions’ Merseyside derby defeat to Everton last weekend with an adductor problem.
The England midfielder underwent corrective surgery and will begin an immediate rehabilitation programme to ready himself for a return to action.
Although no specific timescale has been placed on Henderson’s absence, the Reds confirmed on Friday he will not be avaiable until April at the earliest.
That means he will miss the next five games for Jurgen Klopp’s side in the Premier League as well as the Champions League last-16 tie with RB Leipzig.
The 30-year-old’s lay-off is the latest injury woe to befall Liverpool, who already lost Virgil van Dijk, Joe Gomez and Joel Matip for the season.
Henderson and midfield partner Fabinho had attempted to fill the void left in defence for large parts of the campaign but have both succumbed to injury.
The Brazil international missed most of this month’s games with a muscle issue while fellow midfielder James Milner is recovering from a thigh issue.
Diogo Jota is on the cusp of a first-team comeback after two months out with a knee injury picked up in a Champions League dead rubber with Midtjylland.
Other injuries in Liverpool’s failed Premier League title defence this term include Thiago Alcantara, Trent Alexander-Arnold and goalkeeper Alisson.
Henderson himself has been absent with three prior injuries including knee ligament damage sustained during July’s win at Brighton & Hove Albion.
“I don’t know the best case scenario,” admitted Klopp.
“It is not a quick one but we all hope there is still a possibility for him to play a few games this season. We will see.
“We have so many injured players not available at the moment, and most of them are our leaders in the group.”