In San Francisco, Chili Davis tied the game with a two-run homer and Jeff Leonard followed with a bases-empty shot in the bottom of the eighth inning to give San Francisco the win.
The Braves took a 4-0 lead off Andy McGaffigan with the help of bases-empty home runs by Claudell Washington and Dale Murphy, It was Murphy's 19th homer, best in the majors.
The Giants came back with two runs in the sixth, chasing Atlanta starter Ken Dayley, who was promoted from Richmond of the International League Thursday. Darrell Evans singled with one out and Jack Clark followed with his 12th home run of the season.
Reliever Gary Lavelle (5-1) pulled the Giants out of a seventh-inning jam and was the winner when the club got three runs off loser Gene Garber (2-2) in the eighth.
Evans led off with a walk and went to second on Clark's grounder to Garber. Davis then lined a 1-1 pitch over the screen in right for his ninth homer and a 4-4 tie. Two pitches later, Leonard hit his fifth homer.
Davis, who entered the game in a four-for-64 slump, also had a bloop double and a bunt single for a three-hit performance. Murphy ended an 0-for-13 slump with his homer and added a single in the eighth.
"All losses are tough, but we weren't used to something like this because it never happened before," said Braves Manager Joe Torre. "Our bullpen has been doing a great job."
"A win like this is a good pick-me-up for our confidence," said Giants Manager Frank Robinson. "It's good we're getting the long ball, because we're not playing sound, fundamental baseball."