Manchester United's Defensive Dilemma: Carrick's Key Challenge

Michael Carrick stands on the brink of his first full season as Manchester United manager with a smile in public and a knot in his stomach. On paper, he has five central defenders with big reputations and bigger potential. In reality, he has a puzzle that might define his season.

Leny Yoro, Ayden Heaven, Harry Maguire, Matthijs De Ligt and Lisandro Martínez. It sounds like a modern, elite defensive unit: youth, pedigree, leadership, Champions League experience. It should be the foundation of a serious campaign on four fronts – Premier League, FA Cup, Carabao Cup and, for the first time in two years, the Champions League.

Carrick knows better than to trust the brochure.

A manager stepping into the real test

Last season was the audition. Thrown in as caretaker after Ruben Amorim’s sacking in January, Carrick had 17 league games, no distractions from cup competitions, and a dressing room still shaking off the chaos of the Portuguese’s exit. He steadied it.

United lost only twice in those 17 – both 2-1, at Newcastle and Leeds – and conceded 18 goals. Not watertight, but far from the soft-touch side they had often resembled. They climbed to seventh with 32 points from Carrick’s games, still nine adrift of Aston Villa in third, but at least pointing in the right direction.

This season is different. No free hit, no caretaker label, no reduced schedule. Just the relentless grind of four competitions and a manager with only 20 games of United experience behind him. The question is whether the defence he has been handed can carry that weight.

Youth with promise, but no guarantees

The romantic version of United’s future has Yoro and Heaven growing into the club’s next great central partnership. Reality is more fragile.

Yoro is 20, already a £52m signing from Lille in 2024, with 66 appearances behind him and the frame of a modern centre-back: 6ft 3in, quick across the ground, unflustered on the ball. The raw material is there. The problem is the lapses – the odd misjudgement, the occasional switch-off – that still creep in. After two seasons, this is the year when “promising” has to become “reliable”.

Heaven is even greener. The 19-year-old arrived from Arsenal in February 2025 for a nominal fee and forced his way into 11 league starts. He looks like a Carrick defender: technically clean, athletic, with a sturdier build than many in his age group. He knows where he stands in the hierarchy and he said as much: he’s young, he must be patient, 19-year-olds rarely play every week, and he’s waiting for his opportunity.

Patience is a luxury for players. Managers rarely get the same.

If United go into the heart of a season relying on two defenders still learning the craft, the learning curve can quickly turn into a cliff.

Maguire: leader or liability?

At the other end of his career, Maguire is 33 and heading into what feels like a defining campaign of his own. He still brings courage, aerial dominance and the kind of organisational voice that United often lack when he is absent. He has a Carabao Cup winner’s medal from 2024 and the experience of being United captain.

He also has a problem: his legs.

Maguire is one-paced. In a league where transitions are faster, pressing is higher and space behind a high line is ruthlessly attacked, that flaw is impossible to hide for long. Left out of the World Cup by Thomas Tuchel, he now sits in the awkward space between being trusted for his know-how and targeted for his limitations.

Carrick, by instinct and by history, would likely pencil him in as first-choice to start the season, especially alongside Martínez. On paper, that partnership balances left and right, aggression and calm, experience and bite. On grass, it depends entirely on one thing: Martínez’s body.

Martínez: elite, but unreliable

When Lisandro Martínez is fit, he changes United. That was clear again in the 2025 FA Cup final, when he starred in the 2-1 win over Manchester City and drew from Pep Guardiola the ultimate compliment: “a top five centre-back in the world”.

But Carrick cannot build a season on compliments. He has to build it on availability, and that is where Martínez keeps letting him down.

The 28-year-old Argentinian was forced off before half-time in the World Cup final defeat by Spain with a muscle problem, another entry on a growing medical file. His fitness for the opening league game at Hull is still uncertain, and the pattern is becoming familiar: when he plays, United look harder, nastier, more secure. When he doesn’t, everything shifts.

Carrick knows he cannot keep rewriting his defensive plan every time Martínez pulls up. Yet right now, that is exactly the risk.

De Ligt and the long road back

If Martínez is a concern, De Ligt is a full-blown question mark.

The Dutchman, still only 26, has the résumé of a veteran: league titles with Ajax, Juventus and Bayern Munich, big Champions League nights, big pressure, big expectations. He should be the anchor of this defence.

Instead, he has not played since a 2-1 win at Crystal Palace on 30 November, his season wrecked by a back injury that eventually required surgery in May. After the operation he spoke of doing everything since November, pushing through every session, exploring every option just to get back to playing.

The target is a return early in the season. Targets are not guarantees. Backs are unforgiving, especially for defenders who need to twist, jump, and fight for every aerial ball. Until De Ligt strings together games, Carrick has no idea whether he is getting the player who dominated at Ajax or a diminished version trying to manage his body.

So the manager looks at his centre-back pool and sees five names. Behind each one is an asterisk.

A fragile core in a ruthless market

The uncertainty at the heart of United’s defence is thrown into sharper relief by what their rivals are doing.

Manchester City have already gone big, signing Eliott Anderson for £116m. Chelsea have paid even more for Morgan Rogers at £117m. Tottenham have thrown serious money at their rebuild, with Sandro Tonali arriving for £100m and Mateus Fernandes for £85m.

United’s response? Youri Tielemans, 29, from Aston Villa as the headline arrival, plus Andrey Santos, a 22-year-old who started only 11 league games for Chelsea last season. Both are intelligent midfield additions, but neither addresses the question that keeps circling Carrick’s mind: can this defence survive a full season at the top end of English and European football?

For now, the club’s stance is clear. There is no plan to strengthen at centre-back unless one or more of the current group leaves. That is a gamble, not a strategy.

There are still five weeks left in the transfer window. Five weeks for injuries to flare up, for offers to arrive, for panic to set in or for calm, calculated decisions to be made. By 1 September, United could look very different.

At this moment, though, Carrick is preparing to fight on four fronts with a backline that looks anything but fit for purpose. The fixtures are coming, the Champions League anthem is waiting, and the season will not wait for De Ligt’s back, Martínez’s muscles or two teenagers to grow up.