Lisandro Martinez injury is a huge blow for Man Utd - 'The Butcher' has become their most important player

United were just getting used to having Martinez back after he had to undergo a second operation on his foot back in September, when it was clear he was still suffering having fractured his fifth metatarsal last April against Sevilla.

The West Ham game was only Martinez's fourth match back after a four-month layoff, and it was clear the whole squad was gutted for him. Diogo Dalot put out a supportive message on social media and Ten Hag, who brought Martinez to United from Ajax, was visibly upset to see him break down again.

"He is very sad, very disappointed. We all feel really with him. First of all, it is a personal disaster when it is really bad, but also for the team it is really bad because he definitely brings us a lot," the Dutchman said.

"Very bad for him, very bad for the team. It seems bad, we have to wait and make the right diagnosis. In this moment we are very sad, hopefully it is not too bad, but we can only pray."

Ten Hag's prayers have been answered, and it has been revealed that Martinez has not suffered a season-ending cruciate ligament injury as was first feared. He has been diagnosed with a collateral ligament sprain and crucially will not need another operation.

He is expected to return to action within two months at the latest, in time for the business end of the season as United look to salvage a harrowing campaign by making a final push to finish in the top four in the Premier League and win the FA Cup.

The news is also a boost for Argentina as Martinez will be available for the Albiceleste's bid to retain the Copa America. But while there is some relief after the diagnosis, even the best-case scenario of six weeks is out is too long for United, who have come to rely on Martinez to an unhealthy extent.

Martinez has been a revelation for United since signing from Ajax for £47 million ($59m) in the summer of 2022, quickly silencing doubters such as Jamie Carragher who wrote him off due to his lack of height. After a short bedding-in process, he proved to be hard as nails and not afraid of anyone, living up to the nickname 'The Butcher' he earned back in Argentina, and soon had a chant penned by United fans for his bruising reputation.

"He is so aggressive, he’s really good with his feet, he’s really good at tackling, so you cannot write him off just because he’s maybe not the height you expect him to be," said former United defender Daley Blind. "But I think he showed himself directly that he is capable of everything in the Premier League."

United benefitted from Martinez's bone-crunching challenges on Sunday, and it was plain to see that he was relishing being back in the thick of the action against West Ham, with the Stretford End yelling 'Argentina' every time he won the ball back.

Martinez is also a highly-intelligent defender, and West Ham manager David Moyes credited him for the role he played in preventing Emerson Palmieri from scoring after he had dispossessed Harry Maguire early in the second half. The Italy international spooned the ball over the bar, but Moyes praised Martinez for his positioning, which prevented him from squaring to Jarrod Bowen.

"Emerson was through, and maybe Jarrod should keep his run going and give him a square-pass option for the tap-in, or maybe it would affect Martinez, who did a good job in defending and forcing Emerson to keep on the ball. And then, before you know it, you’ve lost the ball," said the former United boss.

And it should be no wonder that United were so concerned at the sight of their inspirational centre-back falling injured again. The contrast between their record with Martinez and without him is stark.

Of the 47 matches the Argentine has played since signing from Ajax, United have won 32, drawn four and lost 12. But in the 48 games he has not started, they have won only 25, drawn eight and lost 14. That's a win rate of 68 per cent with him in the starting XI and just 52 per cent without him.

It is little coincidence that when Martinez fractured his metatarsal in that fateful match against Sevilla last season, United were 2-0 up and cruising towards victory in their Europa League quarter-final first leg, setting them up perfectly for the second leg and giving them an ideal platform to make the semis.

After he had to be carried off the pitch in agony by two Sevilla players, United shipped two goals in the final minutes. And without Martinez, they were butchered themselves at the Sanchez-Pizjuan, being thrashed 3-0.

They continued to struggle without him, only seeing off Brighton in the FA Cup semi-finals thanks to a penalty shootout before being comfortably beaten 2-1 by Manchester City in the final, while they merely limped over the line into the top four in the Premier League after defeats at Brighton and West Ham.

Admittedly, Martinez was far from his best at the start of this season and United still lost four times with him in the starting line-up, against Bayern Munich, Brighton, Arsenal and Tottenham. But there was a clear mitigating factor: Martinez had not properly recovered from the metatarsal injury and needed a second operation.

United's results got even worse in his absence, with their defence looking particularly abject. They suffered diabolical defeats to Bournemouth, Newcastle, Manchester City and Nottingham Forest in the league. Their Champions League form was even worse, losing four of their six games to finish bottom of their group while shipping a shocking 15 goals (only Royal Antwerp conceded more).

As well as missing Martinez's defensive steel, United really struggle without the composure and control the Argentine gives them in defence. His distribution and his ability to bring the ball out from the back are even more impressive than his ball-winning abilities.

His long passing lifts United on an attacking level as he can start promising moves with one swing of his boot, such as when Alejandro Garnacho hammered the crossbar against Newport County after latching on to a Martinez pass. And it helps them defensively, as United can hold on to the ball for longer.

"When you've got composed players at the back like him and like Shaw, especially those two on the left side, it gives you balance but it also discourages the press," said former Liverpool midfielder Danny Murphy on Match Of The Day 2. "Because the first time they play and get a bit of joy, teams think 'Hold on we're on the back foot here', so I think his composure on the ball will be greatly missed."

Moyes also remarked that, along with Casemiro, who has also missed a big chunk of the season through injury, Martinez gave United "a much greater degree of calmness on the ball in their build-up play. I think it makes them look more comfortable."

Despite all the money United have spent on their squad in the last few years, they do not possess any central defender who comes close to Martinez when it comes to ball-playing ability. Maguire has improved this season, but still cannot move the ball around with purpose or confidence, and against West Ham he lost it in a dangerous area, spared only by Martinez's positioning and Emerson's wastefulness. And it cannot be forgotten that Ten Hag wanted to sell Maguire last summer.

Jonny Evans has done well on occasions this season, but his sumptuous assist against Burnley aside, has not displayed much passing ability or composure and has stood out more for his organisational skills and his experience. Not even Raphael Varane can match Martinez's dribbling and passing ability, while Victor Lindelof does not even come close.

Martinez has also instilled a winning mentality in the team, the product of lifting successive league titles with Ajax plus the World Cup and Copa America with Argentina. His thirst for success is contagious: just see how much he celebrated the Carabao Cup triumph at Wembley, even though he had hoisted the biggest prize in football just two months previously.

Shaw has described Martinez as "an absolute monster," saying "I could see his qualities, feel the passion that he brings, how aggressive he is" as soon as the Argentine started working with the squad.

"He's dominant, he's aggressive, he's a leader, he communicates well, he shows character and he is there in big moments," said Rio Ferdinand last year, summing up Martinez's range of qualities.

Those qualities have raised United's game in the past and will do again when Martinez returns in April. Until then, they have little choice but to grit their teeth and grind away in his absence while looking forward to his return, which cannot come soon enough.