Ferguson expects the Belgian to be a United first teamer.
"Of course, it was great. He is a big coach, the boss, and it's a good feeling. I always want to do better and better but it felt good and was a really big step for me. I hope to achieve something at Manchester United," Januzaj told manutd.com.
Ferguson is a regular at U21 and U18 games.
"I love this," continued the Belgian. "He is a big coach, you can't say anything more about him as he is one of the best in the world, but I don't think other team's managers come to watch the Under-18s and the Reserves. But it's really professional here and I really like it at United. I feel good here."