How long Kobbie Mainoo could be out for as Thomas Tuchel issues injury update on Man Utd midfielder

England manager Thomas Tuchel has revealed that Kobbie Mainoo missed Saturday's World Cup 2026 third-place playoff win over France due to a back problem.

The Manchester United academy prospect would have been hopeful of earning his first minutes of the competition in the bronze-medal match after being snubbed in every game leading up to the semi-finals.

Tuchel preferred Declan Rice and Elliot Anderson as his starting midfield duo, while Reece James was also favoured in a central role if the former was worse for wear.

Mainoo was a notable absentee from the England teamsheet on Saturday, and the national team quickly clarified that he was missing due to injury.

Fans on social media were sceptical, but Tuchel quickly sought to quash any speculation in his post-game press conference, saying: "Kobbie was injured in the last training session. He felt a sharp pain in the back."

How long could Kobbie Mainoo be out for with back injury?

Mainoo is one of two notable names to be struggling with a back problem right now, as Arsenal's William Saliba suffered the same fate in France's semi-final defeat to Spain.

The Arsenal defender had been managing the chronic problem for months before exacerbating the issue at the World Cup, and there were fears he could miss four to five months had he required an operation.

Arsenal are now adopting a conservative treatment approach with Saliba, but it remains to be seen how long he is out for, while the severity of Mainoo's problem also remains up in the air.

However, if the midfielder has only picked up a minor strain, he should be fully operational again within a couple of weeks, meaning he will be fit for the start of the new Premier League campaign.

A Grade 2 strain could sideline Mainoo for three to six weeks, though, while a Grade 3 issue - such as a herniated disc or spinal fracture - would require a two to four-month recovery process.

There is no suggestion that Mainoo has suffered a severe problem, though, and the 21-year-old was set to miss a large chunk of pre-season anyway given his World Cup involvement.

Man United kicked off their pre-season with a disappointing 1-0 loss to Wrexham on Saturday, and Michael Carrick's side next face Rosenborg on Friday.

Do Man United need to sign another midfielder?

Mainoo is now one of two Man United midfield injury victims alongside ACL absentee Manuel Ugarte, whose serious injury may have destroyed his hopes of earning a move away from Old Trafford this summer.

As a result, new signings Youri Tielemans and Andrey Santos are now leading a youthful midfield pack also encompassing Toby Collyer (22), Dan Gore (21) and Tyler Fletcher (19), all of whom are yet to enjoy a first-team breakthrough.

Unless Carrick plans on giving Collyer a shot or deploying Mason Mount in a deeper role, Man United are in need of a pure number six to replace Casemiro, but 'serious doubts' have emerged over a possible £100m deal.