Jamie Carragher has said that Liverpool need a centre-back, ideally to be signed in the January transfer window.
The Reds, who are without Joel Matip out until the New Year with injury, have relied on Joe Gomez filling in alongside regulars Dejan Lovren and Ragnar Klavan.
Jurgen Klopp's side were heavily linked with Southampton defender Virgil van Dijk in the summer window, and Carragher believes that the Dutchman should still be the club's top priority.
"We all know Van Dijk was the one [Klopp] wanted, so because he never got another centre-back, now he's waiting until maybe January or the end of the season, I hope it's January.
"It's a big concern [that Matip and Lovren don't play enough]. You always build any top team from your goalkeepers and your centre-backs. When me and Sami Hyypia played, we were fortunate as we never got injured and these two just get injured too much.
"Liverpool need quality. Basically one of those two needs to be third choice. You need a centre-back to come in and one of those to play with him, and (Ragnar) Klavan is your number four."
Liverpool play Arsenal on Friday evening looking to keep their place in the Premier League's top four.
