The 22-year-old Brown was in the starting lineup for the Phillies' game against the Arizona Diamondbacks, playing right field and batting sixth. Brown batted .327 with 20 homers and 68 RBIs in 93 games at Double-A Reading and Lehigh Valley.
"I'm pretty nervous, but a good nervous," Brown said before the Philles' 7-1 win over the Diamondbacks. "I'm trying to get the first game under my belt and get rolling."
Brown shook off any nerves he had, recording two hits and two RBIs in his major league debut.
Victorino has an abdominal strain on his left side. He was injured diving back to first base during a pickoff attempt in Tuesday night's win over Arizona. Victorino stayed in and left after making a catch later in the game. He was batting .250 with a career-high 15 homers, 53 RBIs and 20 steals.
Brown said he heard about Victorino's injury Tuesday from a fan in right field at Coca-Cola Park in Allentown, Pa., and the thought of getting called up dawned on him after the game. When he got the official word around noon on Wednesday, Brown said it was one his greatest moments.
"I almost passed out," Brown said. "It's one of the best days of my life. I've been playing since I was three and this is the ultimate goal."
The 6-foot-5, 200-pounder never doubted his ability would land him in the big leagues, saying it was just a matter of time.
"I'm very confident in myself and set big goals," he said. "I was just waiting for [Phillies GM] Ruben [Amaro] and those guys to make the call."
While he realizes the intense spotlight he'll be under, Brown said he'll try to do the simple things that have allowed him to have success to this point.
"I'm just going to try to have fun and do the things I've been doing," he said. "I hope I can go out and put up the same numbers I've been putting up. Of course there's pressure, but I try to keep that in the back of my mind and try to have fun."
Philadelphia manager Charlie Manuel is impressed with Brown, who spent much of spring training with the Phillies.
Asked what stuck out the most, Manuel said, "how much he likes to play. He puts the fat part of the bat on the ball and makes good contact. He has a chance to be a really good hitter."
Manuel expects Brown to be a middle-of-the-order hitter.
"I'll gradually work him in and get his confidence as high as I can and all the sudden I'll turn him loose," Manuel said. "He's a talented kid."
In other injury news, Manuel said shortstop Jimmy Rollins was still sore. Manuel targeted this weekend as a possible return to the lineup for Rollins, who bruised his left foot on Monday after fouling a ball off the foot.
Information from The Associated Press was used in this report.