In the coming years, Manchester United will need to spend an additional £100 million to upgrade Casemiro, according to Jamie Carragher, who believes they made a big mistake by signing him last summer.

The 31-year-old helped the team win the Carabao Cup in his first season in English football after moving from Real Madrid to Old Trafford in a £70 million move last summer.

He struggled greatly in Monday night's 1-0 victory over Wolves, though, as the visitors' running from deep caused him all kinds of issues. Gary Neville even went as far as to claim that he was "torn to shreds." He did, nevertheless, occasionally display signs of ageing.

Sofyan Amrabat of Fiorentina is the midfielder most likely to join United as they search for a replacement to complement him and help with the defensive load.

Carragher, however, believes that by buying Casemiro, who lacks the vigour and mobility of younger midfielders at rival teams, United have put themselves in a precarious position and that they will soon need to replace him in order to remain competitive.

I never thought Casemiro would be a good investment. Not because he hasn't been a world-class player—he has—but rather because he's reached a point in his career where he can't fully recoup United's enormous investment, the former Liverpool defender wrote in his column for The Telegraph.

'He was a panic buy when he joined a year ago, bought right after the failed attempt to sign Frenkie de Jong from Barcelona; an ageing, stellar name signed for big money and on a massive salary to appease growing fan resentment, despite the fact that he will need to be replaced with a similarly massive outlay two years from now.

He is just the type of acquisition that United has been steering clear of this summer as they look to the future.

Casemiro struggled against Wolves, according to Carragher, who noted that Casemiro "lacked the dynamism and energy required for such a responsible position" and was "too often isolated."

Erik ten Hag is already in a position where he must redesign his midfield because Casemiro lacks the stamina to work by himself. Having someone beside him will be beneficial, but it won't go back in time and create the 25-year-old who won the Bernabeu lottery.

His peak years were passed by the time he came to Old Trafford, therefore his overall contribution could only be useful for a limited time. Is that a resource-wise use of them?

Casemiro, a recent addition to Manchester United, is "ready to go."

"United are now being strongly linked with players like Sofyan Amrabat to help Casemiro protect their back line, but they did not challenge Arsenal and Chelsea for Moises Caicedo, Romeo Lavia, Enzo Fernandez, or Declan Rice because they believed Casemiro was the same type of midfielder when they paid a premium for him.

"That shows how unwise it was for them to pay so much," someone said. Real Madrid just won't let players of that calibre go until they believe they have gotten the best of them. Given that Casemiro still has four years left on his rumoured £300,000-per-week Old Trafford contract, United is still facing a huge financial obligation. They have already lost the opportunity to purchase a younger substitute.

They won't be title challengers until they identify a Rodri, Caicedo, or Rice of their own, he continued.

The current market says they will need another £100 million for the midfielder to do so for the following five years after spending £70 million for someone who could do the job five years ago but will continue to struggle to achieve his prior high standards.