Liverpool defender Virgil van Dijk is "out for more than a month" with a hamstring problem, says manager Jurgen Klopp.
Van Dijk, 31, has played in all of Liverpool's league matches this season.
"The diagnosis was pretty harsh. We're talking about weeks, more than a month," said Klopp before Saturday's FA Cup tie with Wolves.
"I hope it goes quick. It's hard for him, but he has played an incredible amount of games in recent years."
Joel Matip, Ibrahima Konate, Joe Gomez and Nathaniel Phillips are Klopp's other options at centre-back.
In better news for Liverpool, midfielder Jordan Henderson is available once again after missing the Brentford game with concussion.