Ruben Amorim 'working with Kobbie Mainoo' on defending as Man Utd's homegrown hero looks to win spot back from Casemiro

Brazil international Casemiro must sit out United’s Premier League trip to Brentford after collecting two yellow cards and a red during a dramatic 2-1 victory over Chelsea at Old Trafford. Somebody will be required to fill the No.6 spot next to club captain Bruno Fernandes when a visit to west London is paid.

Mainoo could be the man for the job, with the England international having waited patiently for his big break this season. Despite having 76 appearances for United and 10 senior England caps to his name, the youngster has started just one game in the 2025-26 campaign - which delivered a humbling Carabao Cup defeat to League Two side Grimsby.

Mainoo is, however, still part of Amorim’s thinking, with the Portuguese said to be putting on intense training sessions that are intended to help a hot prospect improve certain areas of his game.

A source has told The Sun: "Ruben has been working with Kobbie on his defensive plays and skills, talking with him a lot about defensive commitment in order to try him alongside Bruno at some point. Kobbie also has the ability to play as a number six, which is important since Casemiro has had some ups and downs, will be suspended, and [Manuel] Ugarte hasn’t fully convinced Amorim yet. Kobbie’s athleticism and hunger to succeed are seen as very important by Ruben, and he is clearly showing him that he wants him committed and ready to help in any central midfield position, even now as a number six, since the team lacks impact in that role."

The insider went on to say: "Kobbie is a player Ruben likes a lot, but he also wants him to keep working hard, be ready to make sacrifices, and understand that opportunities and playing time will come over the course of a long season. Ruben trusts Kobbie’s talent and sees that he has been working very hard and giving everything in training lately. He likes seeing Kobbie in “warrior mode” lately and enjoys that he has developed this kind of mentality.

"Ruben loves Kobbie’s athleticism, football IQ, and skillset. He is challenging him to make him better and sees him as a strong option to play as a defensive midfielder in certain games and situations. Ruben feels that using Kobbie as a six in some matches will help him become a better, more complete player and keep improving to reach his full potential."

Amorim has spoken of wanting to see more from Mainoo, saying of the 3-4-3 system that he favours: "The way I play is completely different from the last manager. I watched a lot of Premier League games when I was in Portugal. You can feel the Manchester United team was really transitional. Sometimes I looked at Kobbie Mainoo and felt he was the only guy who calmed the game down. Now we have other players who can do that and we play a different game.

"Kobbie is really good at controlling the game, but if he plays as an eight he has to reach the box and return. Sometimes he has to cover a lot of space with just two [players]. He could play as a six (defensive midfielder) but sometimes he passes the ball and goes away, which is not a reference as a six. We have to balance everything. He has the technical ability but he needs to understand the position better. He needs to play in different speeds - sometimes lower, sometimes faster. He can improve on that."

There was talk of Mainoo wanting out of Old Trafford over the summer, having seen his minutes dwindle, but Amorim insists a sale was never on the cards. He has said: "I didn't have a conversation with him before the window closed because I didn't want Kobbie Mainoo thinking that I was having a conversation with him just to hold on to him. I believe in him a lot. He is a top player. But some of you think that Kobbie Mainoo is already done [a complete player]. I think he can do so much better. For some guys [talent] is enough, but for him it is not. Maybe it's not fair, but I think I'm helping Kobbie and that's it."

Mainoo is under contract until the summer of 2027, with little progress being made in efforts to put an extension in place. He needs to find regular game time this season if a place in Thomas Tuchel’s England squad for the 2026 World Cup is to be earned.