Brian McCann hit a go-ahead three-run double during a six-run sixth inning, Kris Medlen pitched neatly into the seventh and Atlanta beat the Phillies 7-5 on Wednesday night.
Martin Prado had a pair of homers and Matt Diaz also connected for the National League East-leading Braves, who roughed up Jamie Moyer (9-8).
"It's two out of three. That's all it is," Braves manager Bobby Cox said, downplaying the importance of the series.
But the two-time NL championship Phillies now are six games behind Atlanta with their seventh loss in 10 games. It's the furthest they've been out of first place since Sept. 13, 2007 when they were 6 1/2 behind the New York Mets. The Phillies overcame a seven-game deficit with 17 to play to win the first of three consecutive division titles.
"We're having a tough time right now," Phillies manager Charlie Manuel said. "We're kind of banged-up, but if we're going to compete, we can't be chasing two teams. People say we're a second-half team. I'm not saying we're not, but we don't want to get too far behind."
Ryan Howard and Shane Victorino homered for Philadelphia.
The Phillies are missing several key players, including five-time All-Star Chase Utley and Placido Polanco. But Manuel thinks they're also missing an intangible.
"We try, but that little spark, that little swagger, just enough cockiness to make you good, something's missing there; that's what we got to get back," Manuel said.
Medlen (6-1) allowed four runs and seven hits in 6w innings. The Braves are 10-1 in his starts this season.
Billy Wagner tossed a perfect ninth for his 19th save in 22 chances.