Matt Garza will start for the Brewers against John Lamb in Game 1, and Wily Peralta will face Keyvius Sampson in Game 2.
This was the Reds' fifth postponement of the season and their third at home.
It was Cincinnati's 21st rain delay of the season and the 15th at Great American Ball Park. The Reds have waited out 27 hours and 45 minutes' worth of delays this season, including 21 hours and 46 minutes at home.
"We've had interruption [before], but we haven't had necessarily the cancellations and just massive amount of time missed to delay," Reds manager Bryan Price said.