Liverpool central defender Joe Gomez has been injured on international duty with England.
The 23-year-old suffered the injury during the build-up to the game against the Republic of Ireland on Thursday.
England manager Gareth Southgate is expected to provide an update on the seriousness of the issue at a news conference on Wednesday.
Liverpool already have Dutch centre-back Virgil van Dijk facing a lengthy spell on the sidelines.
Van Dijk has had surgery on a knee ligament injury picked up against Everton in a 2-2 draw on 17 October.
The Premier League champions have also been without Fabinho, who had been deputising in defence for Van Dijk, because of a hamstring injury.
Additionally, Liverpool have an injury concern over right-back Trent Alexander-Arnold, who was taken off during a 1-1 draw against Manchester City on Sunday.
Phil McNulty, chief football writer
Gomez’s injury while on England duty means Liverpool manager Jurgen Klopp now faces a serious defensive crisis – and will only increase his growing frustration at the packed fixture schedules.
Joel Matip played alongside Gomez at Etihad Stadium but he was only just back from injury and has a chequered fitness record. Gomez was effectively Klopp’s linchpin in that position, with youngsters Rhys Williams and Nat Phillips also stepping in since Van Dijk and Fabinho were sidelined.
The news that Gomez could now be facing a spell on the sidelines leaves Klopp with a serious problem as the fixtures continue to come thick and fast, surely meaning he will enter the transfer market for a central defender when the window opens in January.
It is also a personal blow for Gomez, who has suffered serious injuries in the past, one of which saw him restricted to only a last-minute appearance as a substitute in Champions League final victory against Tottenham in Madrid in 2019.
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