With one out and runners on second and third and Aaron Hill at the plate in the fifth, the skies opened up and umpires quickly called the game.
The Brewers got on the board in the first when former D-backs slugger Mark Reynolds singled home Logan Schafer, who had tripled to right.
The D-backs tied things up in the second when Mark Trumbo led off with a homer to left-center off Hiram Burgos.
Trumbo was back in the starting lineup one day after being scratched due to a bruised left heel.
The D-backs took a 2-1 lead in the third when Paul Goldschmidt drew a two-out walk from Michael Olmsted and scored when Miguel Montero followed with a double to the gap in right.
In his first start of the spring, Arizona right-hander Trevor Cahill allowed one run on two hits while striking out four in 3 1/3 innings.
Up next: The D-backs head across Scottsdale to visit the Giants on Sunday afternoon. It will be the first start of the spring for lefty Wade Miley. Arizona will get its first look at Tim Hudson in a Giants uniform, as the right-hander is scheduled to start for San Francisco.