Januzaj burst onto the scene in former manager David Moyes' solitary season in charge of the Red Devils and was rewarded with Ryan Giggs' famous no.11 jersey by Louis van Gaal as a teenager.
However, the Belgium international struggled to replicate the form he showed under Moyes when he scored five goals and registered eight assists in 38 games across all competitions.
Loan spells at Borussia Dortmund and Sunderland followed before making a permanent switch to LaLiga outfit Real Sociedad, where he's reinvigorated his career as a permanent fixture in their starting line-up.
And ahead of their UEFA Europa League meeting this week the fleet-footed winger has opened up about potentially returning to Old Trafford, with the club leaving the door open with the buy-back clause.
"Football is football, anything can happen. I'm in the best moment of my career, I'm enjoying my football here, and then whatever will come for me, we will see," he told MEN.
"I'm really happy here for the moment, I have still one more year left of my contract here, so a lot of things could happen, if I stay or if I go, but for the moment I'm really happy to stay here and I'm happy here, so it's the most important for me."
On the difficult spell under van Gaal, the 12-time capped Belgium winger concedes his style of play simply didn't meet the philosophy for his 3-4-1-2 tactical system.
"I didn't want to leave United but when you don't get game-time, you're not happy because of a few people, then you cannot stay there and you have to move on and play your football somewhere else," Janauzaj admits.
"If you don't have the right people, the right coaches who can push you further then it would be really difficult for you to show yourself on the pitch, to express yourself."