Lucas Leiva is set for five to six weeks on the sidelines with a quad injury, Liverpool manager Jurgen Klopp has confirmed.
The Brazilian midfielder missed Wednesday's 3-0 win over Manchester City due to the problem, which he sustained taking a penalty in Liverpool's League Cup final shoot-out loss to the same opponents last weekend.
And the 29-year-old will now be out of action for a lengthy spell as Liverpool push to finish the Premier League season in a European qualification place.
"I've never heard of an injury like this, after taking a penalty," Klopp said at his pre-match media conference ahead of Sunday's trip to Crystal Palace.
"It's more serious than we thought. It's a quad injury. Five or six weeks."
Daniel Sturridge is back in full training after missing the win over City, while Mamadou Sakho was restricted to a light session on Friday following a head injury that kept him out of the same fixture.
Liverpool are six points outside the top four going into the match at Selhurst Park.
But Klopp is adamant Liverpool have what it takes to bridge that gap and return to Europe's elite club competition.
"Six points is not the world. We have to show it, consistency has not been our hobby until now. We need to improve that.
"Our starting position isn't a masterclass but we are still in a good enough position to achieve something."