The Philadelphia Union have signed 14-year-old Cavan Sullivan to the largest homegrown contract in Major League Soccer history, with an agreement to transfer the phenom to English Premier League power Manchester City after he turns 18.

Philadelphia was not authorized to discuss details about the built-in transfer to Man City, but Sullivan confirmed to ESPN that Man City's involvement contributed to his decision to sign with his hometown club. His older brother, Quinn, 20, has been a first-team player since 2021.

"I've always wanted to start my career here because this is my home and I've always been on the sidelines of Quinn's games and I've been in and around the facility when my uncle worked here," Sullivan told ESPN. "So, I've always been inspired and to play in front of this culture, and these fans are special.

- Stream on ESPN+: LaLiga, Bundesliga, more (U.S.)

"But I also think the collaboration between the Union and the City Group was -- I think that did it for me. I always watch Man City. They're like every kid's dream team. For [Philadelphia and Man City] to come together and agree on something -- I sat with my family and my agents and we decided that it was the best plan."

Financial details were not disclosed.

Sullivan is the fifth-youngest player to a sign a first-team contract in league history. If he appears for the Union before July 29 -- which is the expectation -- he would surpass onetime prodigy Freddy Adu as the youngest player to appear in MLS.

"I think it would be cool to obviously have my first record, but it doesn't really matter to me if I beat it or not," Sullivan said of Adu's record. "I mean, everyone's on their own journey. It's not really where you start, it's about where you finish."

On whether Sullivan will debut before July 29, Union coach Jim Curtin told ESPN: "If he's healthy, he'll do it."

Ever since Adu flamed out and his career turned into a cautionary tale of unfair expectations and unmet hype, there has been a collective temptation in the United States to cringe at comparing him to others who have come since. By signing at such an early age, Cavan Sullivan -- and his family and the club -- knew they were inviting outsized expectations in a similar vein.

By signing with the Union, staying at home with his parents and playing with his older brother, the hope is that remaining in a familiar, comfortable environment will ease the transition.

"I think he's a pretty mature kid. I think he gets some of it," said Brendan Sullivan, Cavan's father. "That's not to say we don't think there's going to be bumps along the way. We definitely know that. And I think that's part of the reason this collaboration between the Union and City Group is so important, because he really does have a safety net here.

"I mean, Jim Curtin is integral in the fact that this deal even got done. I think he's on board, and he's willing to give Cavan the tutelage he needs to get him up to running and at the level."

The Curtin and Sullivan families have a long shared history. Curtin played for Cavan's grandfather, Larry Sullivan, as a teenager and as a college player at Villanova, where Larry Sullivan was the head soccer coach from 1991 to 2007. As such, Curtin has been aware of Cavan Sullivan's development since he was very young.

"I knew Quinn, and Cavan was the youngest son. As it often goes, the youngest tries to keep up with his older brothers -- he has two older twin brothers that are also good players," Curtin said. "So, you'd see them around on different sporting fields all over the Philadelphia area, and the legend of Cavan kind of grew."

Still, it would have been impossible to foresee this kind of rise.

Cavan Sullivan's maternal grandfather is from Germany, and he has held a German passport from a young age. When Quinn started going on trials with European clubs as a young teenager, Cavan would also get to go, which is when the realistic possibility of a European move started to crystalize. About four years ago, they both trialed at Borussia Dortmund -- Quinn with the U17s; Cavan with the U13s or U14s -- and Cavan remembers thinking from then on that he could see himself eventually playing in Europe.

For now, the focus is on breaking through with the Union in a meaningful way.

"I guess my goal is just to become a regular player within the next two years," he said. "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."

If Sullivan progresses rapidly, there is also the possibility he could move to Europe as early as 16, but in that scenario, he would not be permitted to play in England. City Football Group owns clubs in Spain (Girona), Belgium (Lommel S.K.), Italy (Palermo) and France (Troyes) that could serve as potential developmental stops.

"When the time is right, the game tells the truth," Curtin said. "You can trick it for a game or two or a half, but over the course of a season, if Cavan has a season where it shows that he's above the level in MLS, he'll move on."

Sullivan's best position is still yet to be determined, but he's an attacker who is dynamic with the ball at his feet and confident taking on defenders. Curtin said he could serve as a second striker or an attacking player and that his versatility will be an asset for the Union.

"I would say the big word is 'playmaker,'" Sullivan said. "That's what I try and be every game, every training. I think I'm good on the dribble. My decision-making is pretty good, and my vision on the field is one of my qualities."

Sullivan has appeared twice for the Union II in MLS Next Pro, registering one assist in 58 minutes.

"I haven't really done anything yet, haven't even made my debut," Sullivan said. "So, there's still a lot of room for improvement, a lot of development to go. But definitely still excited for what's ahead."