Mainoo hopeful of making England's Euro 2024 squad after being 'shocked' by first call-up
Initially part of the Under-21s squad, he was drafted into manager Gareth Southgate's team on Tuesday before England host Brazil on Saturday and Belgium on March 26.
Mainoo has made 20 appearances for United across all competitions this season, scoring two goals. The academy graduate has shown calmness and dependability on the pitch, dribbling swiftly through heated midfield battles.
"I was shocked and happy (to get the call-up). It's been a whirlwind of emotions, a pretty mad couple of days," Mainoo told BBC Radio 5 on Wednesday.
"I had to adapt quickly to the Premier League. It's very demanding physically, and also mentally, so it's been tough. But I feel like I've found my feet a bit now and I'm enjoying it."
Asked about his hopes of making the squad for this year's Euros, Mainoo said: "I think that's the end goal for the season, to get into that squad."
England are grouped with Slovenia, Denmark and Serbia at Euro 2024, which begins on June 14.