Then on a 1-0 pitch, Braun took off from third and Lucroy laid down a perfect bunt, allowing him to come across untouched with the winning run.
John Axford (1-1) picked up the win with a scoreless ninth. Brewers starter Randy Wolf limited the Giants to one earned run on three hits over 7 1/3 innings.
Carlos Gomez hit an inside-the-park homer in the first inning for Milwaukee, which evened their three-game series with the Giants at one win apiece.
The Giants, who trailed 2-0 for most of the contest, got a game-tying RBI single in the eighth inning from Pat Burrell.
San Francisco starter Jonathan Sanchez went seven innings, yielding two runs on only two hits.