Sullivan is highly-regarded as one of the most talented youngsters in the world in his age group, and a move to a world powerhouse like Man City was always on the cards.
The 14-year-old has high ambitions, though, despite his young age.
"I guess my goal is just to become a regular player within the next two years," he added to ESPN. "And then after that I would hope to be a starter. I guess that's from the 16 to 18 age window. And then right when I'm 18 I hope to be at the level of the Man City first team."
However, despite the hype around his deal, the contractual City move and all of the expectations on his plate, he remains level-headed about where he's at as a footballer in his career.
"I haven't really done anything yet, haven't even made my debut. so, there's still a lot of room for improvement, a lot of development to go. But definitely still excited for what's ahead," he explained.