The Philadelphia Union have signed 14-year-old talent Cavan Sullivan to a professional contract with the player expected to join Manchester City when he reaches 18.

Sullivan, an academy product, already plays for the Union's reserve team but the new deal will allow him to play in Major League Soccer and other competitions for the first team.

Sullivan, a United States Under-15 international, had attracted interest from a number of big-name foreign clubs.

Premier League clubs are not allowed to sign foreign players until they are 18 so Sullivan is expected to stay with Philadelphia until he reaches that age in September, 2027.

"The collaboration between the Union and the City Group was -- I think (the thing) that did it for me," Sullivan told ESPN.

"I always watch Man City. They're like every kid's dream team. For them to come together and agree on something -- I sat with my family and my agents and we decided that it was the best plan."

Sullivan's older brother, Quinn, plays for the Union's first team and two other brothers, Ronan and Declan, are in the club's youth academy.

"I've been watching my home team, the Union, for as long as I remember and hoped that one day I'd get the chance to play for my city in front of my family, friends, and fans," Sullivan said in the club's release.

"Being able to not only play for the Union but to be able to play with my brother is a dream come true. I will give everything I have to this club and hope to help bring home some hardware. I'm thankful for the opportunity and hope to make Philadelphia proud."

Union coach Jim Curtin, speaking at a press conference, declined to discuss when the player would make his first team debut.

The youngest player to take the field in MLS was Freddy Adu, who made his MLS debut at 14 years and 306 days old in 2004.

"Cavan is 14. His job here will be to be a kid and play and reach his full potential. Our job here is to create an environment where can thrive," Curtin said.

"Cavan is a generational talent. That is not the opinion of just the Philadelphia Union. That is globally through scouts, clubs all over the world."

Sullivan stuck a slightly different tone, however, noting he has a lot of development still to undergo.

"To be honest, nothing really has happened yet and the work starts now. I still have a lot to do," he said.

"My main goal is to win MLS Cup, so development starts now. It does feel nice but there's still a lot of work to do for my part and a lot of room to grow."