HOUSTON, Texas — Manchester United are sweating on an injury suffered by Kobbie Mainoo after the midfielder was left on crutches and wearing a protective boot following the 2-0 defeat to Real Madrid.

The 18-year-old was a surprise inclusion in the team to face the Spanish giants at NRG Stadium on Wednesday but he lasted just two minutes before being substituted.

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Madrid forward Rodrygo collided with Mainoo after being tripped by Casemiro and the teenager was seen wearing a plastic boot on his left foot as he left the stadium.

“You can never tell straight after a game, we have to wait for what it is,” Erik ten Hag said when asked about the injury after the game.

“Hopefully he is not too bad and chances will come. I wanted to see what levels he could play against Arsenal, we were pleased with his performance, and I wanted to see if he could repeat that and set conclusions, now I have to wait for the diagnosis.”

United were beaten in Houston thanks to goals from Madrid’s new signings, Jude Bellingham and Joselu.

Mason Mount and Marcus Rashford had chances for United but Madrid were never seriously tested and deserved their victory.

“For us it was a bad start, straight away an injury for Kobbie Mainoo, he has to get off and then we straight away concede — offside, onside, it’s very difficult to see,” said Ten Hag.

“Of course Real Madrid are a very good team, very good football players but we created some very good chances. We have to be more clinical and score goals from those situations.

“Overall, I have seen some good stuff and from this we know we are in the right direction against a good opponent in a complicated system. I am happy about it.”

One positive for Ten Hag was the performance of goalkeeper Andre Onana, who was handed his United debut following his move from Inter Milan.

The Cameroon international sat out the win over Arsenal in New Jersey on Saturday but started against Real Madrid and looked composed with the ball at his feet.

“I think [Onana had] a good performance, solid,” said Ten Hag.

“Two very good saves, so he was there in the moment the team needed him. He did his job, he integrated well in our team.”