The fast rising star is expected to be named in Scotland's squad for the games against Costa Rica and Hungary this month.
"You've got the majority of the ball (playing for United) and sometimes (with Scotland) that's not going to be the case", Fletcher told BBC Scotland's Sportsound.
And, according to The Times, the Man United youngster has come to a decision.
"It is not easy and then national team will be just a outcome of his work at the club but I can't confirm at all that both national teams have contacted him". All of a sudden you're putting pressure on yourself to win the game single-handedly. He's a fantastic young player and it's great for us as a country.
"He's somebody who is going to play for the team, he's got the superstars around him and sometimes you need somebody to do that extra bit of work and be a real team player". It's about working hard and being willing to go that extra hard yard to cover for some of the flair players.
"Last season, he was nearly leaving the club to go somewhere". "I feel good, fit, strong".
"Scotland have improved the last qualification campaign and if he feels more Scottish than English fair play to the kid".