The Scottish boss lasted just 10 months in the Old Trafford hotseat after succeeding Sir Alex Ferguson in 2013, winning 27 and losing 15 of his 52 matches.
But Moyes, now coaching in Spain with Real Sociedad, was responsible for introducing Brussels-born starlet Januzaj to the Red Devils' first team.
I decided to take him on tour with the first team within minutes of watching him
Making a brief appearance in the season-opening Community Shield against Wigan in August, the talented teenager would go on to make 35 appearances in all competitions in 2013/14, scoring four goals, before starting for Belgium against South Korea at the World Cup.
Speaking exclusively in the February 2015 of FourFourTwo, Moyes reveals how he needed just "minutes" to decide he was good enough to take on pre-season.
"Some youngsters get overawed. Not Adnan. I realised that when he came to train with the first team soon after I joined," he says.
"I decided to take him on tour with the first team within minutes of watching him. He wasn't timid, but hungry to succeed. He was one of the bright spots.
"He possesses a level of self-assured arrogance, which is a positive, as he's not too arrogant. On the contrary, he's a bright lad who is mature for his age.
"He's a wonderfully gifted player with great balance and the ability to go past people. When I see his poise on the ball, he has characteristics of Johan Cruyff."
Read the full interview with David Moyes in the February 2015 issue of FourFourTwo, which hails the globe's finest 23 players under 23 and features exclusive chats with Ross Barkley, Mario Gotze, Koke, Antoine Griezmann, Marco Verratti, Marquinhos, Aymeric Laporte and Ryan Gauld. Plus, FFT goes One-on-One with Alan Shearer, meets the joint-managers with a difference at Whitstable Town and asks Adebayo Akinfenwa some silly questions.
