The Vancouver Whitecaps gave 15-year-old Alphonso Davies a professional contract on Friday night and an MLS debut a day a later.
Davies, who already played for the Caps in four Canadian Championship games this year, entered Saturday's 2-2 draw against Orlando City in the 76th minute.
He is the first player to sign a pro deal from Vancouver's USL affiliate WFC2 and the third-youngest signing in MLS history at 15 years, 262 days.
Only D.C. United's Freddy Adu (14 years, 168 days) in 2004 and Toronto FC's Fuad Ibrahim (15 years, 130 days) were younger when they signed their MLS pro contracts.
New England's Diego Fagundez and Philadelphia's Zach Pfeffer were also 15 upon signing.
"Alphonso is a bright young player who has earned this opportunity," Whitecaps coach Carl Robinson said in a statement. "He still has a lot of hard work ahead of him, but at this point in time we felt this was the best move for his development and for the club.
"This is another great example of our player pathway and we hope he will be the first of many WFC2 players to make the next step."
The midfielder is needed to fill in for Kekuta Manneh, who had surgery on Friday after breaking his foot last weekend.
Davies also played for the Whitecaps in preseason friendlies and scored against the Houston Dynamo on Feb. 9.
"This is a dream come true," Davies said upon signing his deal. "I've grown so much since joining the Residency program last year, and have continued to learn from the first-team players and coaching staff. Coming to Vancouver was the best decision of my life.
"I'm so thankful to the club for having faith in me and I can't wait to get started in MLS."
Davies was born in Liberia but grew up in Edmonton and is a Canada youth international and played for the under-20 team in a friendly in March.