Liverpool's defensive woes have worsened after Fabinho was withdrawn midway through the first half of their Champions League clash with FC Midtjylland.
The Brazil international pulled up shortly before the half-hour mark against the Danes under no contact from the opposition.
Academy defender Rhys Williams was introduced for his second run out in the European competition after his late cameo against Ajax last week.
Fabinho will be assessed by the club's medical staff ahead of Saturday's visit from West Ham in the Premier League.
But the setback has come at a terrible time for manager Jurgen Klopp.
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With Virgil van Dijk set for surgery on an ACL injury and Joel Matip still struggling to prove his long-term fitness, Klopp will be sweating on the diagnosis for Fabinho, who has been asked to drop back into defence for much of the season so far.
Matip has missed the last three games and will again be checked over ahead of the game at the weekend with the Hammers.
As well as Williams, Liverpool also have teenager Billy Koumetio and Nat Phillips on their books.
But the Premier League champions are facing a senior centre-back shortage as things stand.
