One of the main priorities for England boss Gareth Southgate is finding a solution to his defensive dilemma, both in terms of shape and personnel.
With the Three Lions setting up with three at the back more often than not, there are spaces up for grabs in the centre of the defence ahead of the rescheduled Euros next summer.
Southgate is spoiled for choice, but just who are his strongest options? 90min takes a look....
14. Rob Holding
Rob Holding may not be the most glamorous defender around, but he is a solid option for Southgate and has established himself as a regular in the Arsenal team.
Maintaining fitness has been an issue for Holding in recent years, with these spells on the sidelines disrupting his rhythm and confidence. While he's still quite some way off, Holding could be an option as part of a back three if injuries begin to pile up.
13. Chris Smalling
Smalling hasn't featured for his nation since 2017, but there is a reason why Roma tried so hard to make his loan move from Manchester United permanent. He was excellent for the Italian giants in 2019/20.
The defender was dropped back in 2017 due to his supposed inability to build attacks from the back compared to others. But he's improved his game in Italy, and remains a strong overall defender - which is exactly what England need.
Still, however, Southgate will likely overlook him.
12. James Tarkowski
There's no denying Tarkowski's abilities as a defender, with his no-nonsense style of play and awareness. But he has fallen down the pecking order somewhat in more recent times, and Burnley's slow start to the 2020/21 season hasn't helped matters.
Not considered one of the most technically gifted defenders available to Southgate either, it would likely either take injuries or an upturn in the Clarets' form before he finds himself recalled to the Three Lions squad.
11. Adam Webster
While an outsider, Webster meets all the requirements to be part of the England squad under Southgate. The 25-year-old has been excellent so far in 2020/21, and was even handed the captain's armband at Brighton in the absence of Lewis Dunk.
More than comfortable on both feet, Webster is calm in possession, looking to break the lines and find his teammates in pockets of space. Equally, an authoritative and commanding presence, Webster is a real threat in both boxes.
A senior call-up may not be too far away.
10. Mason Holgate
Holgate would have been in Southgate's thinking regarding a senior call-up before suffering a toe injury during pre-season.
But having now returned, the 24-year-old will be looking to rediscover the form he showed during 2019/20 in order to fight his way into the conversation for an England call-up.
However, with strength in depth at the back now for Carlo Ancelotti, Holgate will have to deliver at club level before being given any chance on the senior stage.
9. John Stones
Oh dear. Where did it go wrong for John Stones?
The Manchester City defender is in desperate need of either a move away from the Etihad in January or a run in the first team if he is to have any chance of being called back up by Southgate ahead of the rescheduled Euros next summer.
The first one seems like a far more likely scenario.
8. Ezri Konsa
Aston Villa have made an excellent start to the 2020/21 season, and while the likes of Jack Grealish have grabbed the headlines, central defender Ezri Konsa has quietly been one of Dean Smith's best formers.
The 23-year-old has formed a strong partnership at the back with Tyrone Mings, with his pace, reading of the game and no-nonsense defending complimenting his partner's style of play.
Konsa has been outstanding and he deserves to be rewarded for his form with a senior call-up.
7. Fikayo Tomori
Having been called up to the senior squad last season after a solid start to Premier League life under Frank Lampard at Chelsea, Tomori has fallen out of favour at both club and international level.
It's unclear what's gone on behind closed doors, but it seems Tomori has work to do to work his way back into Lampard's - and in turn Southgate's - plans.
Not the best with the ball at his feet, but more than makes up for that with his pace in recoveries.
6. Michael Keane
Keane is back playing some of his best football at club level under Carlo Ancelotti, not only putting in strong showings at the back, but also popping up with goals from set pieces.
The 27-year-old has all the tools to claim a starting spot in the heart of the England defence, but he will need to continue taking his chances when presented to him if he is to hold down the position.
5. Tyrone Mings
Mings may not make the most tackles, but he reads the game well and has been key to Villa's defensive record so far in 2020/21.
As a left-footer, the 27-year-old adds a different dimension to the Three Lions backline as well, as he is able to step forward with the ball naturally and find his teammates ahead of him. This allows the defence to explore different avenues in the attack - something which is key for Southgate.
4. Eric Dier
Dier has established himself as a key part of Tottenham's defence in 2020/21, putting in assured and confident displays.
Almost certain to be part of the England squad next summer (injuries permitting, of course), Dier is very much in contention for a starting spot at the back as well. As well as being able to read the game well, nipping in to win the ball back, Dier is also very comfortable starting attacks with his excellent passing abilities.
3. Conor Coady
Coady could just be the central defender England have been looking for in recent times. The Wolves captain is constantly looking to communicate with those around him, instructing his teammates and ensuring performance levels don't drop.
But as well as being a commanding defender, he has the ability to pick out the forwards with exceptional diagonal passes, getting his side playing on the front foot. A leader with outstanding quality both defensively and when on the ball, Coady will be desperate to keep his spot in the starting lineup.
2. Joe Gomez
Gomez will miss a 'significant' portion of the rest of the season after undergoing surgery on a serious knee injury. As a result, the England international faces a race against time to be fit for the delayed Euros.
But if he is able to return for Liverpool before the end of the 2020/21 season and can regain full match sharpness, he will be in Southgate's plans.
It remains to be seen how his recovery goes, but Gomez will still be targeting a return ahead of the Euros.
1. Harry Maguire
Is he everyone's favourite defender? No.
Is he perfect? No.
But is he England's best centre-back and a certain starter should he maintain fitness? Absolutely.
The Manchester United captain reads the game well, can comfortably play out from the back, and poses a real threat from set pieces too. Maguire also leads the defensive line with authority and confidence. A certain starter.