Manager Brendan Rodgers has been looking for defensive reinforcements for much of the summer and has already landed centre-back Dejan Lovren from Southampton.
But there is fierce competition for places at the club, and it is going to be a hard task to keep all of these defenders happy - so one would think that a couple of defenders currently at the club will make way.
Andre Wisdom has already taken up the opportunity of moving to West Bromwich Albion on loan to continue his development whilst it looks likely that a signing from last summer in Tiago Ilori will also leave the club on a short-term basis.
But there are still several defenders at the club, and not all of them are going to have the opportunity to play regularly, even if Liverpool have more games to contend with this season with the Champions League. So here is a look to see who may be playing their football elsewhere when the transfer window shuts at the start of next month:
Daniel Agger: Probably the most obvious candidate as the uncertainty over his future continues. Agger has been linked with a potential move to Barcelona, whilst the chairman of his former club Brondby has been quoted saying he would like to sign the Liverpool vice-captain this summer. The Reds are also reportedly willing to listen to offers for the Dane.
Kolo Toure: Toure has been linked with a move away to Trabzonspor. The Ivory Coast international has a year left on his contract, but Brendan Rodgers has been quoted recently saying that the side needs players like the experienced ex-Arsenal and Manchester City man. Wouldn't be surprising if he stayed as cover, but equally if he ended his spell on Merseyside.
Martin Kelly: Kelly's situation is an interesting one. He has played centre-back at youth level but during his time in the first team he has been playing at right-back. With the arrival of Manquillo, he could be as low as fourth in the pecking order. His luck with injuries has been horrendous as last season was spent, in part, trying to get his fitness to a level where he could play some games a long time on the sidelines with a serious knee injury. One or two Premier League clubs are rumoured to be interested in him.
It is hard to see any other players leaving for now. The club seem pretty willing to keep hold of Glen Johnson despite the right-back entering the final year of his contract, but there has been nothing to suggest the Reds are keen to cash in right now.
Jon Flanagan impressed last season and may not play as much in the Premier League as he did last term but his ability to play on both the left and right flanks should lead to him sticking around at the club for this season.
Jose Enrique has recovered from a long knee-injury and is likely to provide stern competition for Moreno and is likely to get some game time this season, as either cover or as a rotational option.
Which defenders do you think could leave Liverpool before the transfer window shuts?