South African Fortune was at Old Trafford when Ronaldo arrived as a teenager from Sporting Lisbon in 2003. By the time that he had left for Real Madrid in 2009, the Portuguese attacker was regarded by many to be one of the best players in world football.
Eighteen-year-old Januzaj has himself broken into the United senior side this season and having seen the young Belgian action, Fortune has likened the two playmakers.
"He has so much belief and confidence in his own ability, and that's hard to see in young players these days. He reminds me of Ronaldo when he arrived. He believes in himself and that takes you far in this game," he told FIFA.com. "He has great talent and he is a level-headed guy. He is doing incredibly well, he is already one of the key players in the team, and hopefully that will continue.
"If Adnan can follow what Ronaldo did it would be unbelievable for himself and the club. Adnan has exactly the same mentality. I don't think Ronaldo lacks confidence, and that is why he is one of the best players in the world. Adnan still has a long way to go. He has [made] a fantastic start though and I wish him the best."
Januzaj was part of the United side that defeated Norwich City 4-0 in the League Cup last night.