Cavan Sullivan broke Freddy Adu's longstanding record as the youngest player to feature for a senior MLS side when he took the field for the Philadelphia Union in their match against the New England Revolution on Wednesday.

Sullivan, who is 14 years, 293 days old and was called into the senior squad for the first time on Tuesday, came on late in the second half to break the record held by Adu in a runaway 5-1 win for the Union.

The young American signed the largest homegrown contract in Major League Soccer history on May 9, in a deal that stipulates Sullivan will transfer to English Premier League power Manchester City after he turns 18.

Sullivan, whose brother Quinn also plays for the Union and scored on Wednesday in the win, didn't have many opportunities on the ball, but he did have one good run toward the end of the game that ended with a powerful shot on goal from outside the penalty area.

Following the match, Adu posted on social media: "Big congrats to Cavan Sullivan for his record breaking debut today. That's a hard record to break and the kid did it. Well done and good luck my man."

Sullivan is also younger than any player who has appeared in the NBA, NHL, NFL, WNBA or Major League Baseball since at least 1970, according to the Elias Sports Bureau. Andrew Bynum, who debuted for the Los Angeles Lakers in 2005 at the age of 18 years, 6 days, holds that mark.

The youngest debut in the five biggest soccer leagues around the world since at least 1988 was by Ethan Nwaneri, who came on for Arsenal in 2022 at 15 years, 181 days.

Adu held the record as the youngest to play for an MLS senior side since he took the field for D.C. United against the San Jose Earthquakes on April 3, 2004, at the age of 14 years, 306 days. He scored 23 goals over a club career that took him from the United States to Europe and back to the U.S. again, where he last played for the Las Vegas Lights of the USL.

At 16 years, 234 days, Adu earned his first cap for the United States senior team -- still a record -- in a friendly against Canada. He scored the first of his two goals for the USMNT in a 2-0 win over Guatemala on Nov. 19, 2008.

Sullivan was born in Philadelphia to two soccer-playing parents, and he joined the Union's youth academy four years ago. He made his professional debut in March for the Philadelphia Union II in MLS' developmental league.

At his signing, Sullivan said: "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. I mean, everyone's on their own journey. It's not really where you start, it's about where you finish."

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.

"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."

ESPN's Kyle Bonagura and The Associated Press contributed to this story.