The Rockies assigned Holliday to their Triple-A affiliate, the Colorado Springs Sky Sox, at the outset of the 2004 season, intending for him to spend much of the season there. Injuries to outfielders Preston Wilson and Larry Walker expedited his progress to the Major Leagues after just six games with Colorado Springs. He made his major league debut in left field on April 16 at Busch Memorial Stadium against one of his future teams, the St. Louis Cardinals. Holliday went hitless in three at-bats. Two days after his debut, Holliday recorded his first career hit, a single, and then, RBI against the Cardinals' Woody Williams, doubling in Kit Pellow. Holliday's first career home run came against José Lima of the Los Angeles Dodgers on April 22. Five days later, he, Jeromy Burnitz, and Charles Johnson collaborated for back-to-back-to-back home runs against the Florida Marlins, the sixth such occasion in franchise history.