The 18-year-old was United's match-winner against Sunderland at the weekend, becoming only the second player to score twice on his Premier League debut for the club.
Januzaj's display at the Stadium of Light has sparked a rush to secure his international future given he is eligible for numerous nations, but he is only thinking about establishing himself at Old Trafford.
Belgium, Croatia, Albania and Serbia are among the nations vying to have Januzaj play for them but that choice is far from his thoughts at present.
"At the moment, international football isn't something that I've thought a lot about," he told United Review.
"I know that, first, I have to concentrate on what I do for United, because that is the most important part of my career right now.
"I want to play well for United and give everything for my club.
"I'm really enjoying myself, I played quite a few games in the reserves last season and thought I did well.
"From there, I had the chance to go on the summer tour and it was a good opportunity for me to show what I can do for the team. It was a great experience and ever since I've been working hard.
"I want to play in as many games as I can and become the best payer I can possibly be. I know that I need to keep working hard every day to achieve that. I have to be ready, ready to take my chance.
"I'm confident in my ability and believe I can help the team."
David Moyes unleashed Januzaj after being impressed during pre-season and the Scot has stated United are doing everything they can to tie him down to a lengthy contract.