Liverpool legend Jamie Carragher says the knee injury suffered by Virgil van Dijk has cost Jurgen Klopp's team 12 points this season.
And the Scouser is again urging Klopp to buy a new centre-half in January.
"The injury to Virgil Van Dijk alone will cost Liverpool between nine and 12 points over the course of this season," he said.
"And although Fabinho has proved a fantastic deputy at the back, Joel Matip's ongoing problems means, to me at least, that it is inconceivable that Liverpool will not sign another centre-half at the earliest opportunity.
"I cannot understand the logic of not doing so. The club needed one anyway."
Carragher, writing in the Telegraph, added: "If Matip continues to be in and out of the side, and then Fabinho gets injured, how can Liverpool expect to perform at the highest level with only the inexperienced Rhys Williams and Nat Phillips to step in? That is too big a risk.
"The way Liverpool have dealt with the loss of key players so far shows they will still take some stopping, but it will not be as one-sided as last year and failing to sign another defender will only lift the hopes of everyone else.
"Jurgen Klopp will be cursing a missed opportunity if Liverpool do not retain their title. Liverpool are the best team in England, but circumstances have opened the door for everyone with dreams of catching them."