Liverpool have been busy this summer, splashing the cash on midfield reinforcements Alexis Mac Allister and Dominik Szoboszlai, but there is still a need for a new centre-back.
Trent Alexander-Arnold's tactical tweak, which saw him prioritise midfield work over defending, put a little extra strain on Liverpool's back line towards the end of last season and so Jurgen Klopp would be wise to recruit another high-level starter, which would allow the boss to re-balance his starting lineup.
Doubts over the long-term futures of Joel Matip, Joe Gomez and Nat Phillips could see Liverpool opt for a real reshuffle at the back this summer, but just how much money they have to spend on that position remains to be seen.
Here's a look at the defenders Liverpool should be trying to sign this summer.
Levi Colwill
Age: 20
Club: Chelsea
The dream signing here is, without a doubt, Chelsea centre-back Levi Colwill.
Behind the scenes, Liverpool have been keeping a very close eye on the 20-year-old, who excelled at Brighton and is looking for guarantees of a regular starting role from Chelsea before he commits to staying next season.
Unfortunately for Liverpool, who made a second enquiry about Colwill recently, the message from Chelsea has been clear. They are not looking to sell and it is going to take something enormous to change their minds.
There's a bit of a waiting game to be played here. Colwill is away with the England Under-21s and won't speak to Chelsea boss Mauricio Pochettino before their pre-season tour begins, but if that conversation doesn't go well, Liverpool could pounce.
A left-footed, ball-playing defender, Colwill looks like an absolute superstar of both the present and the future. If there's a deal to be done, Liverpool will look to do it.
Goncalo Inacio
Age: 21
Club: Sporting CP
The Portuguese league has produced a series of ready-made Premier League players recently and there's no reason to believe 21-year-old Sporting CP defender Goncalo Inacio wouldn't continue that trend.
Inacio is a prolific, accurate passer who thrives on making things happen from the back, and that sort of creativity would be a valuable asset in a Liverpool backline that already prides itself on its ability to overload in the attacking third.
He doesn't shirk his defensive duties either, with his one-on-one ability and timing of a tackle both standing out.
It's a similar style of play to Colwill but from a player who would likely cost half the price, so it's no surprise to see Liverpool considering Inacio.
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Aymeric Laporte
Age: 29
Club: Manchester City
Aymeric Laporte's future at Manchester City is far from clear as the Premier League champions look to splash out on Josko Gvardiol. Could Liverpool take advantage?
City are more than happy to do business with their Premier League rivals for the right price and may not need too much convincing to sell Laporte, who has just two years remaining on his contract.
Laporte's time in England has not always been perfect but, when the Spain international is on form, there are few better.
What makes Laporte such an appealing prospect is his knowledge of the Premier League. There would be no need for a settling-in period and the 29-year-old should be primed to hit the ground running.
There's competition for Laporte's signature from across Europe but the chance to remain in northwest England could help lure him to Anfield.
Micky van de Ven
Age: 22
Club: Wolfsburg
Liverpool love a Dutch defender. Virgil van Dijk will go down in history as one of the club's best-ever - could Micky van de Ven be the heir to his throne?
At 22, the towering Van de Ven is still in the early stages of his senior career but is already causing real excitement. The Dutch Under-21 international is another excellent left-sided passer, but his dribbling ability sets him apart from the rest.
Van de Ven is so comfortable in possession that he has even been used as a left-back, and so he could offer some much-needed cover for Andy Robertson on the outside of defence as well as in the centre.
Tottenham are pushing to land Van de Ven's signature, so if Liverpool don't want to miss out, they may have to act soon.
Facundo Medina
Ligue 1 side Lens conceded just 29 goals in 38 games last season. Only Barcelona (20) and Napoli (28) bettered that return, which should tell you the sort of elite company Lens were keeping.
Lots of their success was down to Facundo Medina, whose third year with the club saw him take a huge leap and emerge as one of Ligue 1's finest defensive talents.
The 24-year-old Argentine spent most of the campaign on the left side of a 3-4-2-1 setup and did not disappoint at either end of the field, shining with the ball at his feet but proving stubborn and aggressive at the back.
Medina only inked a new contract in January and Lens are under no illusion of the talent they have on their hands, but Liverpool should have the financial power needed to get them talking.
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This article was originally published on 90min as Five centre-backs Liverpool should be trying to sign this summer.