Joey Votto and Laynce Nix clubbed solo home runs off of Todd Coffey in the 13th to pull out the win for the Reds.
The Brewers had a chance to win in the 9th, but Ryan Braun ran threw a stop sign at third base and was tossed out at the plate.
Felipe Lopez had four hits, including his 8th home run of the season for the Brewers. Jeff Suppan returned from the disabled list and struggled, pitching just 4 1/3 innings, allowing 4 runs on 9 hits.
The loss drops the Brewers 3-games under .500 at 61-64. They trail the first place St. Louis Cardinals by 11 games. Braden Looper pitches game two of the series for the Brewers tonight.