Liverpool captain Jordan Henderson will be sidelined for at least five weeks after undergoing groin surgery, the Premier League champions said on Friday.
The 30-year-old England international sustained the injury during Saturday's 2-0 home defeat by Everton.
"Henderson has successfully had a corrective procedure carried out on the adductor injury. He will begin a rehabilitation programme immediately," Liverpool said in a statement.
"No specific timescale is being placed upon his return; however, he is ruled out initially until after the March international break," the statement continued.
Henderson will miss Premier League games against Sheffield United, Chelsea, Fulham and Wolverhampton Wanderers, as well as the Champions League last-16 second leg against Leipzig.
Liverpool are sixth in the standings with 40 points from 25 games, five points adrift of fourth-placed West Ham United.