Mainoo started against Charlton in the quarter-final of the League Cup on Tuesday night, alongside Fred and Scott McTominay in a three-man midfield. The youngster played 60 minutes and it was a competent first-team debut at Old Trafford.
The 17-year-old played an instrumental role in the Under-18s winning the FA Youth Cup last season and academy staff have long considered him a leading light in his age group, which has been recognised by Ten Hag during his reign.
After making two matchday squads in the Premier League this season, Mainoo was desperate to make his first-team debut and he was given that opportunity against Charlton, with Ten Hag explaining before the match that his start was &aposwell deserved&apos.
Mainoo reflected on making his debut after the Reds&apos 3-0 win against Charlton and he said &aposhe felt at home&apos at Old Trafford.
“It&aposs an unbelievable feeling. I&aposve been at this club all my life, it&aposs all led to tonight. To have my family here watching me, surrounding me, it&aposs just amazing,” Mainoo told MUTV. “All my immediate family were here, I think bringing anyone else would be too much!
“They were all here, supporting me, and I waved to them after the game. Pretty much today [found out he was starting], the team sheet was put up and I was starting, so it was a bit of shock but I thought, I&aposve got to do a job.
“Of course, a few butterflies but it was more just exciting. I played at Old Trafford in the Youth Cup final and I remember that feeling. It was an amazing feeling and to have that again was brilliant. I&aposve been in training with the lads quite a few times.
“They all made me feel welcome, giving me words of advice and encouragement, so I felt at home. It was a tough game physically, but I believe in the lads and thought we should always come out on top.
“To be able to follow him (Casemiro) closely and watch him in training is an honour and for him to come on for me tonight is crazy.”