Jurgen Klopp has told Liverpool's official website that Dejan Lovren faces a race against time to be fit for the first leg with Bayern Munich in the Champions League next week.
Lovren and Joe Gomez have not travelled with Liverpool to Marbella for their mid-season training camp.
The Croatian is sidelined with a hamstring injury and Klopp admits it isn't a 'good sign' that he and Gomez haven't travelled.
He told Liverpool's official website: "Dejan is not here and Joe is not here.
“That’s never a good sign, I would say, but we will try everything to make Dejan available for Munich. It will be a tight race."
It's potentially a big, big worry for Liverpool because it's possible that Joel Matip will be the Reds' only recognised centre-back for the clash with Bayern on Tuesday.
Virgil van Dijk is suspended after picking up three yellow cards in six group-stage games earlier in the season, while Gomez underwent surgery a little earlier this month.
Klopp has previously used Fabinho as a centre-back this season, but the German also told the club's official website that even he is injured at the moment, though he expects him back in time.