Brown, starting in right field and batting cleanup for the U.S. team in the minor-league showcase at Angel Stadium, showed his speed in his only at-bat, beating out a deep grounder to short and driving in a run.
But he was almost picked off first base, and then overran second on a shallow single to center, scrambling back safely only after second baseman Brett Lawrie of the World team was unable to make the play.
The 22-year-old was replaced by a pinch-runner after reaching third base.
Don Baylor, manager of the U.S. team, made the decision that Brown should come out after Brown felt pain leaving the batter's box and had trouble on the bases.
"I just told him it was a little tight. He said no need for me to stay in there, and he took me out of the game," Brown said.
"For me, I'm such a competitor, I probably would have tried to stay in the game. They made the right decision."
Chuck LaMar, the Phillies' assistant general manager for player development, described the move as "precautionary" after getting a report.
"Nothing's pulled. Nothing's strained. We think it's extremely minor," LaMar said in a telephone interview. "Right now, it's strictly precautionary. They have a duty to protect him."
The U.S. stars won the game, 9-1.
Brown, a 6-foot-5, 205-pound outfielder recently promoted to triple-A Lehigh Valley, is batting .364 with four home runs and 12 RBIs after 15 games with the IronPigs, raising speculation about whether he might be called up to the Phillies before the end of the season.
He batted .318 with 15 homers in 65 games at double-A Reading this season before he moved up to Lehigh Valley.
"Everything's going great," Brown said before the game. "We've been winning as of late. I'm just having fun, and we'll see what's going to happen the rest of the year."
He said he leaves it to others to wonder when he will reach the majors. Some do, with Raul Ibanez playing less than his best and Jayson Werth poised to become a free agent after the season.
"Getting to the big leagues? I don't worry," Brown said. "I know it will come someday."
Brown takes the same attitude about trade talk - and so far the Phillies have refused to part with him, including when his name came up in the Roy Halladay talks.
"I just play," Brown said. "I try not to worry about trade rumors."
If there is a plan for his development, Brown said he doesn't know it.
"I leave that up to [Phillies general manager Ruben Amaro Jr.] and those guys," he said, adding that the biggest adjustment to triple A has been seeing more off-speed pitches.
LaMar said Brown's triple-A transition has gone "quite well," but did not address his future.
"He's a fine young prospect," he said. "Hopefully, he'll continue to have success."
Brown's visit to Angel Stadium was one of only a few appearances he has made in major-league ballparks, including high school showcases at Atlanta's Turner Field.
Before the game, he looked around his stall with an eye for a souvenir before he returns to the chain hotels and bus rides of the minor leagues.
"It's an honor and a privilege to be here," said Brown, whose father, Robert, joined him from Atlanta for the game.
"Hopefully I'll keep the jerseys. I have two here, so one for my dad, my mom . . ."
One of them is game-worn. But only barely.