Manchester United midfielder Casemiro has been struggling with poor form this season AFP / Oli SCARFF

Manchester United midfielder Casemiro reportedly has regrets over his decision to join the Old Trafford club.

Casemiro enjoyed a nine-year decorated run at Real Madrid, where he was a part of a high-profile midfield alongside Luka Modric and Toni Kroos. Casemiro's trophy-laden journey at Real Madrid ended last summer when he made a £70million-move to Manchester United.

The trio established a formidable partnership in the midfield that helped Los Blancos win three La Liga titles and dominate in Europe, winning five UEFA Champions League trophies.

Casemiro's arrival at Manchester United ahead of the 2022-23 season made an instant impact as he helped Erik ten Hag transform the team, adding balance, control and much-needed structure. In Casemiro's debut season, the Red Devils ended their six-year trophy drought with the EFL Cup title, while also reaching the FA Cup final and recording a top-three Premier League finish.

The 31-year-old midfielder made a total of 51 competitive appearances during the 2022-23 campaign, contributing seven goals and seven assists for Manchester United.

However, Casemiro's form has taken a dip this season, raising questions over his place in Ten Hag's side. The arrivals of Sofyan Amrabat and Mason Mount this summer have only added to the competition for midfield places, while Kobbie Mainoo will feature once he returns from his injury layoff.

Manchester United have lost four out of their nine league games in the 2023-24 season and amid these struggles, it has been reported by Spanish media outlet El Nacional that Casemiro is now regretting his switch from Real Madrid a year ago.

That is despite the Brazilian player sending a text to his agent ahead of his move to Manchester United, after the Red Devils suffered an early-season four-goal loss at Brentford in August 2022, saying: "Tell them I'll fix this."

After the heavy loss to Brentford, Casemiro also phoned Manchester United's football director John Murtough. The call was not to inform Murtough that he was having doubts about leaving Real Madrid - but to give assurances that he couldn't wait to get started in Manchester.

Earlier this year, Casemiro signed a long-term contract with Manchester United. The Brazilian midfielder is now contracted with the Old Trafford side until 2026, with an option to extend by a year. "Case[miro] has signed for four years plus one. He's come to win titles; this month has been hard, but there's nothing else on his mind," said Oscar Ribot, Casemiro's agent, in a recent interview.

The Brazil international missed Manchester United's 2-1 win over Sheffield United in the Premier League on Saturday due to an ankle injury he sustained on international duty earlier this month. He will be looking to return to the side as soon as possible but will sit out the midweek clash against Copenhagen through suspension.