When Mikel Arteta started his first full season in charge of Arsenal, he knew he had some big decisions to make regarding the heart of his defence.
With eight centre-backs on the books, the Spaniard's squad was massively unbalanced and he could see the issues that was going to throw up, so the priority during the summer was reducing the numbers.
Shkodran Mustafi and Sokratis were both told they could leave, but buyers couldn’t be found, while attempts to send William Saliba out on loan also ended in failure – with a deadline-day return to Saint Etienne failing to get over the line.
Konstantinos Mavropanos did at least get a move, with the 23-year-old agreeing to spend the campaign with Stuttgart in the Bundesliga, but Arteta was nonetheless left in a difficult situation.
He knew, given the amount of players he had at his disposal, that certain players were going to find themselves playing very little football – which is far from ideal when it comes to maintaining harmony behind the scenes.
"When you have the squad we have, it’s impossible to have 31 happy players in the camp,” the Gunners boss said. “I don’t know any [other] club who has that.”
Arteta chose to leave Sokrtais out of his squad altogether, with the Greece international not even registered for the Premier League, and Saliba had to make do with a handful of appearances for the Under-23s.
Mustafi, meanwhile, made just three substitute appearances in the Premier League before the turn of the year, although he was at least a regular in the Europa League group stages and also featured in the League Cup defeat by Manchester City.
Still, it was clear that the general situation could not continue, with Arsenal eventually deciding to take the drastic action of cancelling the contracts of both Sokratis and Mustafi in January and sending Saliba out on loan to Nice.
Those moves in the transfer market have left Arteta with a far more manageable defensive department to pick from and, for the first time since he arrived, the Gunners boss finally has a group of centre-backs that has a balanced feel to it.
Gabriel Magalhaes has been excellent since his move in the summer and has been showing signs of getting back to his very best after a difficult couple of months which saw him pick up an injury and catch coronavirus.
David Luiz is arguably in his best run of form for Arsenal, while Pablo Mari and Rob Holding have been excellent at times this season, especially in the few games they have been paired together.
The quartet's impressive displays have left Arteta with a very different sort of dilemma to the one he faced at the start of the season. It's now a case of who starts, and when?
In recent weeks, Gabriel and David Luiz have been Arteta’s preferred duo, despite both being more comfortable as the left sided centre-back when deployed in a pair.
It’s Luiz who has moved over the right, with the former Chelsea star producing some excellent performances alongside his compatriot.
The Brazilians have started each of Arsenal’s last three games and were exceptional in the first leg against Olympiacos - and the north London derby victory against Spurs at the weekend.
Gabriel was also Arsenal’s outstanding player in the 1-0 defeat by Olympiacos on Thursday night in north London and is back to the sort of form he showed at the start of the season, when he was named Arsenal’s player of the month in September, October and November.
Luiz, meanwhile, is delivering consistently on the field again but also continues to be a major presence behind the scenes, especially with the younger players in the squad.
“It’s credit to him because he trains really hard,” Arteta said when asked about Luiz's purple patch.
“This season was really tough for him in the beginning because he’d been through some injuries but he’s kept at it, he understood his role, he knows his role in the team, he’s one of our leaders and he’s so willing to keep improving.
“He knows the things that he’s really good at and the things where there is still room for improvement. He’s a really honest man with himself. He’s won everything and it’s a joy to work with him.
“He’s a great example for [the youngsters]. He’s got a good mixture with them between some banter and then some stick. They all listen to him because of who he is and what he’s done in the game.
"But also because of how he behaves every day, how professional he is and how he goes about the job. He is one of the key role models that we have in our team.”
However, while Luiz and Gabriel have now started together in six of Arsenal’s last nine games in all competitions, it would be no surprise to see Mari and Holding come in for Sunday’s Premier League clash at West Ham.
The pair have only started four games together this season, but in those games they have shown a fine understanding, helping Arsenal to two clean sheets and three wins.
Arteta’s side have conceded just twice in the games when Mari and Holding have started in the centre of defence, with the only defeat coming when they were beaten 1-0 by champions-elect Manchester City.
Arteta’s side have won 75 per cent of the games they've started together, compared to 54.5% when it’s Gabriel and Luiz. They also only concede 0.5 goals per game, far less than the 1.3 goals per game when it’s the two Brazilians.
“He’s a leader, someone that trains really hard,” Arteta said of Mari, who joined Arsenal on a permanent basis from Flamengo last summer. “He’s a professional, a great communicator on the pitch and he gives you some security and stability.”
But of all Arsenal’s centre-backs this season, it’s perhaps Holding who has enjoyed the most consistent campaign so far.
The 25-year-old was close to joining Newcastle last year before Arteta blocked the move and he repaid his manager’s faith by returning the sort of form he was showing before he suffered his cruciate knee injury in 2018 .
Holding has made 27 appearances in all competitions. Of his fellow centre-backs, only Luiz (28) has started more matches – although it’s Holding who tops the charts in terms of minutes played (2,243).
He also averages 0.8 goals conceded per game, which is better than Luiz (1.0) and Gabriel (1.3), and the same as Mari.
The Englishman wins more aerials (2.6) than Luiz and Mari, though, makes more tackles (1.6), clearances (4.3) and also concedes fewer fouls (0.7).
“When you compare how he has evolved in a year’s time, it is incredible,” Arteta said when discussing Holding’s improvement this season.
“It is down to him, how professional he is, how much he wants to learn, how much he puts into every training session and then his character and his personality. He is growing in every aspect. I am really happy with him.”
The form of his centre-backs, and the way they play together, leaves Arteta with a welcome selection headache.
Arsenal’s manager doesn’t have to worry about how many central defenders he has in his squad anymore, but he has to work out who to pair together on a game-by-game basis.
It’s Gabriel and Luiz who appear to be top of the pecking order for now, but the stats show that Mari and Holding have every right to feel like they should be getting a bit more game time.
For Arteta at least, it’s a nice problem to have.