Liverpool have recently revealed that long-serving defender Jamie Carragher will be retiring from professional football at the end of this season, meaning a rather sizable hole will appear in the Reds' back line over the summer.
That, in addition to general concerns over some of the form and quality displayed by other first-team members, means that the Reds are certain to add one new name and could perhaps even bolster their defence by more than that during the transfer window.
Picking a new defender isn't just a simple matter of seeing who makes the most clearances or tackles and throwing them into the team—they have to be able to fit into the tactics of the side, complement their defensive partner (Daniel Agger at present) and display mental and leadership values as well as technical ability.
Not to mention, the centre of the defence is unlikely to be the only area of the Reds' back four which needs some attention this summer.
With that in mind, here are five defenders that Liverpool could be looking to sign come the end of the season.
One of Liverpool's top priorities this summer has to be to sign a new central defender, but one with a particular skill set.
As well as being tough, aggressive and reliable, the Reds need someone who is a good organiser, capable of playing with the ball at his feet and unbeatable aerially.
Other traits the player needs are to be experienced yet relatively young, not cost too much, not already be playing for a top team in the Champions League and be open to leaving this summer.
That might narrow down the options rather considerably, but fortunately for the Reds—should they glance in his direction—Benedikt Howedes ticks all the boxes.
The Schalke defender has just one year remaining on his contract, his team is not looking likely to qualify for European football of any kind next season and he has amassed formidable experience in his 24 years.
The German should be the top name on Liverpool's wanted list this summer and would be an extremely important addition to the team.
The Reds also need to bolster their squad down the left side of defence, a position which has long been a problematic area of the team.
Liverpool have two options: go as big as they can to find a top attacking full-back, or bring in younger players with more potential to get better and improve over the longer term.
One who fits the latter description but still has a lot of ability and experience in the English top flight is Newcastle United's Davide Santon.
The Italian has played over 100 top-flight and Champions League games at age 22 and is adaptable enough to double-up as cover for the right side of defence.
Santon would be an upgrade on the Reds' current options at left-back and has much scope for improvement over the coming seasons.
Shaw, in yellow, is only 17 years of age
One very interesting prospect from the Premier League is Southampton's Luke Shaw.
The 17-year-old only made his top-flight debut earlier this season but has gone on to establish himself as the Saints' first-choice left-back and has a lot of potential.
Shaw has pace, is athletic and strong considering his young age, though of course his inexperience lends itself to problematic situations with regards to positioning.
He can get caught out of position during counter-attacks—but so can any older full-backs who are expected to play high up the pitch.
Shaw could be a relatively expensive signing in terms of what he has already shown in the Premiership, but he also represents a fairly sound bet for return on investment in the future.
Liverpool might need one centre-back this summer, they might need two.
One of the top young defenders in Europe might be available as he is a French regular at international level, but not at club level—PSG's Mamadou Sakho.
Thiago Silva and Alex are the first-choice pairing when fit for the French side, with Sakho a regular in the side because of injury to the other two. Sakho has already admitted that he will leave PSG if he is not a first pick (via Goal.com) as he bids to retain his place for France ahead of the World Cup in 2014.
Strong, powerful in the air and with no shortage of pace, Sakho would give Liverpool a long-term central defender (he is currently 23), with the one interesting asset to note is that he is a left-footer—the same as current first choice Daniel Agger.
As a young prospect target, Liverpool could do worse than taking a serious look at Jores Okore.
The Danish defender is strong and compact, reads the game well and is fearless in the challenge. He has featured in the Champions League this season for Nordsjaelland and has amounted over 50 league appearances in Denmark.
The Reds have Andre Wisdom and Martin Kelly in their squad who both count as young central defenders, albeit ones who ply their trade on the right side for now.
Okore would be a relatively cheaper option than some others, but would perhaps not be ready to step up as the immediate first-team option for Liverpool.