Manchester United have revealed that Kobbie Mainoo has left the club's pre-season tour of the United States to begin treatment on the ankle injury that he suffered against Real Madrid.

The 18-year-old was handed a fourth successive pre-season start in the clash with Carlo Ancelotti's side, but he had to be withdrawn in just the sixth minute of the contest, having suffered an ankle problem when Los Blancos attacker Rodrygo fell on him after being brought down by Casemiro.

Mainoo, who is being tipped to be a first-team regular for the 20-time English champions during the 2023-24 campaign, posted on his official Instagram account that he would be back "in no time".

"I'll be back stronger and in no time," he wrote. "Thanks for your messages of support."

However, Mainoo will now miss Man United's next game with Borussia Dortmund on Sunday evening, and he is also set to be unavailable against Lens and Athletic Bilbao in the team's final two friendlies of the summer.

In a statement on their official website, Man United revealed that the teenager would be unavailable "for the first part of the 2023-24 campaign", although an exact timeframe for his recovery has not been yet.

"Manchester United can confirm that Kobbie Mainoo suffered an ankle injury during the match against Real Madrid on Tour 2023," read the statement.

"The midfielder is expected to be ruled out for the first part of the 2023/24 season. He has flown home from Tour to the UK where further assessment of his injury will take place before a medical decision on the next steps."

Speaking to MUTV after the clash with Real Madrid, former Man United forward Danny Webber claimed that the midfielder could be out for as long as eight weeks due to the nature of the injury.

Mainoo made three appearances for Man United during the 2022-23 campaign, including one outing in the Premier League, featuring against Leicester City in February.

The Red Devils have already boosted their midfield with the signing of Mason Mount this summer, but Fred and Donny van de Beek are in discussions over a move away from the club.

Galatasaray are said to lead the race for Fred, while Real Sociedad are believed to be in talks over a deal for Van de Beek, who is seeking regular action next season.

Departures for the two players would allegedly lead to Man United bringing in Sofyan Amrabat, with various reports suggesting that a deal for the Fiorentina midfielder has already been agreed.