Martinez, 28, helped United to an impressive 2-0 win over rivals Manchester City on Saturday, shackling striker Erling Haaland as the Red Devils kept just their third Premier League clean sheet of a disappointing campaign.

After sacking Ruben Amorim and putting Under-18s boss Darren Fletcher in charge for two games, the result gave Michael Carrick a dream start as United’s new interim head coach.

Before the derby, Martinez was on the receiving end of jibes from former Red Devils midfielders Nicky Butt and Paul Scholes.

Butt said on The Good, The Bad & The Football podcast that Haaland would “pick Martinez up and run with him” and treat the Argentine like a “little toddler”, while Scholes suggested the Norway forward would “throw him in the net” after scoring.

Asked about Scholes’ comment, Martinez said: “Honestly, he can say whatever he wants. I told him already, if he wants to say something to me, he can come to wherever he wants. To my house, wherever. I don’t care.

“And I think for me, I respect the relations when they want to help the club because everyone can talk on the television, but when you see [them] here face to face, no-one says anything in your face.

“So for me, I don’t really care what they say. I just put the focus on my performance, the performance of the team and I give everything to this club until my last day.”

Scholes shared some of Martinez’s comments on an Instagram story on Sunday, and said: “Someone’s had a good game, was really happy for you.”

In response to the invite to Martinez’s house, he added “tea, no sugar” with a tag to the Argentine’s account.​​​​​​​

‘It is about the connection’

United have suffered a miserable season, without any European football and knocked out at the first hurdle in both domestic cup competitions.

It means they face just a 40-game campaign – the fewest they will have played since 1914-15.

Heading into the derby, United had been on a run of one victory in seven games, but an impressive display secured a thoroughly deserved win over their city rivals.

Pep Guardiola’s side were unable to deal with the cacophony of noise from the crowd and intensity of the United players on the pitch, being restricted to their second-lowest expected goals (xG) figure in a league game under the Spaniard.

“It is about the connection,” added Martinez. “It’s about how we represent them on the pitch. If they see us fighting like [that], they will be with us.

“If sometimes our performance wasn’t the best, because they expect a good attitude from us, tackles, the DNA, the blood of Manchester United.”

“And I can really understand because sometimes it’s like ‘what are we doing here?'”

The 27-year-old was taken off on a stretcher late on during the home defeat by Crystal Palace on Sunday with an issue United boss Ruben Amorim described at the time as a “serious situation”.

“Assessment of the injury is ongoing to determine the appropriate course of treatment and the timescale for his rehabilitation,” Manchester United said on Thursday.

“Everyone at Manchester United wishes Lisandro Martinez strength for a successful recovery and we will be supporting him every step of the way.”

Martinez’s absence will be a blow for Amorim as he tries to improve the fortunes of the Old Trafford side.

United are 13th in the Premier League after the defeat by Palace, which was the club’s seventh loss in 13 home games this season.

The news comes at a time when there are renewed doubts over the fitness of left-back Luke Shaw, who has not started a game for United in almost 12 months.

“Licha [Martinez] is really important for us, not just as a football player but the character he has, especially in this hard moment,” Amorim said after the Palace game. “Now it’s time for us to help Licha.”

The Argentine defender’s speculative 25-yard effort took a wicked nick off Sasa Lukic that looped over Bernd Leno 12 minutes from time.

It was the visitors’ only shot on target in a match of few opportunities and lifts The Red Devils – who see boss Amorim turn 40 on Monday – up to 12th spot in the Premier League standings.

Fulham had the better of the first half and went close through Alex Iwobi, but struggled to create much of note following the interval.

The home side had hoped to extend a six-match unbeaten run on home turf, but were thwarted late on as United substitute Toby Collyer cleared Joachim Andersen’s header off the line.

It means Fulham sit in 10th place, eight points adrift of the top five. Improving United are four points further back.

Martinez limped off in the second half after attempting to shield the ball from Hammers defender Vladimir Coufal.

The 26-year-old was playing in only his third league game after more than three months out with a foot injury.

The club said he “is expected to be out of action for at least eight weeks”.

However he will not require surgery.

“We all wish Licha a speedy recovery and look forward to seeing him back on the pitch later in the season,” a club statement added.

United boss Erik ten Hag said after Sunday’s victory that the injury “doesn’t look good” and described it as a “personal disaster” for Martinez.

Martinez missed the latter stages of the 2022-23 season after fracturing a metatarsal in April and suffered “an aggravation” to the injury at the beginning of this campaign.

He missed 22 games in total with his foot injury before making returning against Tottenham on 14 January.

Martinez limped off in the second half after attempting to shield the ball from Hammers defender Vladimir Coufal.

The Argentina international, 26, was playing in only his third league game after more than three months out with a foot injury.

“It doesn’t look good,” said Ten Hag.

“There is a bad concern. We have to wait for a few days for the diagnosis. 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.”

Martinez missed 22 games in total with his foot injury before making his return against Tottenham on 14 January.

The 25-year-old Argentina international missed the end of last season after fracturing a metatarsal in April.

He returned to action at the start of this season but United say he will be sidelined again because of “an aggravation” to the injury.

The club said Martinez “experienced the setback in our Premier League game against Arsenal earlier this month”.

They added: “It has now been determined that he needs a period on the sidelines for recovery and rehabilitation.

“Assessment is ongoing to determine next steps.”

At a news conference on Friday, manager Erik ten Hag said: “It is very sad, for him and the team, because he was not 100% fit.

“I think it was a big difference, the Licha Martinez in the last games and the Licha Martinez we have seen in the last season.”

Martinez faced Wolves, Tottenham and Nottingham Forest before playing in a 3-1 defeat at Arsenal on 3 September.

He went on to play in losses against Brighton and Bayern Munich but then missed wins against Burnley and Crystal Palace.

Martinez joined United from Ajax last July in a deal worth up to £57m and helped them finish third in the Premier League and win the Carabao Cup.

The 25-year-old sustained the injury in United’s 2-2 Europa League quarter-final against Sevilla on Thursday.

Erik ten Hag’s side were reduced to 10 men when Martinez was helped off in the 86th minute with United leading 2-1.

Martinez’s centre-back partner Raphael Varane also sustained an injury and is expected to be out for a few weeks.

“Everyone at Manchester United sends Lisandro and Rapha our best wishes for a speedy recovery,” the club said.

Martinez, a World Cup winner with Argentina, was helped off the pitch at Old Trafford by Sevilla’s Gonzalo Montiel and Marcos Acuna, his international teammates.

He was then placed on a stretcher and carried away for treatment.

Martinez joined United from Ajax last July in a deal worth up to £57m and has played in 27 of United’s Premier League matches this season.

France defender Varane, who joined the club from Real Madrid in August 2021, has made 21 league appearances this season.

He picked up an injury just before half-time and was replaced by Harry Maguire at the interval.

United are fourth in the Premier League with nine games remaining and the club are still in the FA Cup as well as the Europa League.

Speaking before United’s league game against Nottingham Forest on Sunday, manager Ten Hag said: “We have a lot of decent centre-halves. We have proved in the past and in this season that we have four or five very good centre-halves who can do the job.”

Centre-backs Maguire and Victor Lindelof are the likely options to fill in for Martinez and Varane.

Left-back Luke Shaw, who has played at centre-back at times this season, has missed the past two games with a hamstring injury but Ten Hag said the England international could return on Sunday.

The club are also without their top scorer Marcus Rashford, who sustained a muscle injury in United’s win over Everton on Saturday.

After the Forest game, United travel to Sevilla on Thursday for the return leg of their Europa League quarter-final before facing Brighton three days later in an FA Cup semi-final, for which Maguire is suspended.

United, who had used all five substitutes, were reduced to 10 men when defender Martinez was helped off with the home side leading 2-1.

United conceded a 92nd-minute equaliser and are likely to be without Martinez for the return leg next Thursday.

Ten Hag said afterwards that it was not an Achilles tendon injury.

“There was no opponent involved,” said Ten Hag. “We’ll have to wait and see.”

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Martinez, who joined United from Ajax last July in a deal worth up to £57m, looked visibly upset when he went off in the 86th minute.

The World Cup winner with Argentina was helped off the pitch at Old Trafford by Sevilla’s Gonzalo Montiel and Marcos Acuna, who also play for Argentina.

He was then placed on a stretcher and carried away for treatment.

“Let’s hope it’s not so bad, but the fact that he was stretchered away from the technical area and he was in tears, it’s difficult to say what’s happened but he was holding on to his ankle,” said former Manchester United keeper Peter Schmeichel, who was at Old Trafford for BBC Radio 5 Live

United manager Erik ten Hag was keen to be reunited with the 24-year-old, who he signed for Ajax in 2019.

He joins the club on a five-year contract which keeps him at Old Trafford until 2027, with the option of a further year.

“It’s an honour to join this great football club,” Martinez said.

“I’ve worked so hard to get to this moment and, now that I’m here, I’m going to push myself even further.”

Martinez made 120 appearances for Ajax after moving from Argentinian side Defensa y Justicia for £6.3m in 2019, and also played for Newell’s Old Boys.

He has won seven caps for Argentina since making his senior debut in March 2019, and played once in the country’s successful Copa America campaign in 2021.

“I’ve been lucky enough to be part of successful teams in my career and that’s what I want to continue at Manchester United,” he said.

“There will be a lot of work to get to that moment, but I firmly believe that, under this manager and coaches, and together with my new team-mates, we can do it.”

Martinez played under Ten Hag at Ajax and won the Eredivisie title with the club in 2021 and 2022, as well as the Dutch Cup in 2021.

He was also Ajax’s player of the year for the 2021-22 season.

“He’s a warrior and I think the fans will admire him. He has an attitude, fighting spirit,” Ten Hag said.

“He brings aggressiveness in the game, in a good way. I think we need that.

“But he’s also skilful, he can deal with the ball and he’s left-footed.”

United’s football director John Murtough added: “We are delighted that he has chosen to join Manchester United and we are looking forward to seeing him develop further and help the team achieve the success we are aiming for.”

The centre-back is United’s third signing of the summer following the arrivals of Christian Eriksen on a free transfer and Dutch full-back Tyrell Malacia.

Efforts continue to lure Frenkie de Jong to Old Trafford from Barcelona.

The 24-year-old is expected to sign a five-year contract with the option of a further year.

The move, for an initial £49m, is subject to a medical, personal terms being finalised and a UK visa.

The deal includes £8.5m in add-ons and £2.2m in solidarity payments to Martinez’s former clubs.

He made 120 appearances for Ajax after moving from Argentinian side Defensa y Justicia for £6.3m in 2019, and also played for Newell’s Old Boys.

Martinez has won seven caps for Argentina since making his senior debut in March 2019.

He is United’s third summer signing after Tyrell Malacia joined from Feyenoord and Christian Eriksen moved on a free transfer.

The Old Trafford club said it was “delighted” to announce an agreement had been reached with Ajax.

“The transfer is still subject to a medical examination and the contractual agreement of both clubs with the player,” said the Dutch club in a statement.

“The defender is still under contract with Ajax until 30 June, 2025. Ajax agreed a transfer fee of 57.37m euros with the English side. That amount can increase to 67.37m euros through variables.”

Martinez played under new United manager Erik ten Hag at Ajax and won the Eredivisie title with the club in 2021 and 2022, as well as the Dutch Cup in 2021.

He was also Ajax’s player of the year for the 2021-22 season.