 and fourteen-year-old philadelphia union midfielder cave and sullivan became the youngest player in major league soccer history wednesday night and probably the youngest to play in any of the biggest professional sports leagues in the world sullivan was fourteen years and two hundred ninety three days old when he entered philadelphia's home game as a substitute in the eighty fifth minute against the new england revolution that makes about two weeks younger than freddie you do what he made his mls debut in two thousand four forty c united