Reyes made his major league debut on June 10, 2003 against the Texas Rangers, the day before his 20th birthday, going 2-for-4 with a pair of runs scored in a 9–7 loss. Reyes was the first teenager to play for the Mets since Gregg Jefferies in 1987, and the first to start a game since Dwight Gooden in 1984. After the game, Reyes collected the ball from his first career hit and sent it to his parents. Over the following weeks Reyes' impressive form continued, including a grand slam off Jarrod Washburn in an 8–0 victory over the Angels. When Rey Sánchez completed his month-long spell on the DL, Reyes' strong play moved Sánchez to the bench.