Amaury Rivas took the loss after not retiring a batter in the eighth inning. He allowed four runs and four hits.
Arizona minor leaguer Evan Frey had a three-run triple in the eighth.
Craig Breslow (1-1) pitched a scoreless inning for the win and J.J. Putz retired the only batter he faced for his second save.
Diamondbacks starter Josh Collmenter, who has struggled most of the spring, threw three hitless innings. He allowed an unearned run with a walk and a strikeout.
"I knew I had to take care of business," Collmenter said. "I didn't have the greatest spring. That is on record. You can look everything up, but I am going forward now. I can throw all that out of the window."
Notes: Shortstop Stephen Drew will be placed on the disabled list to start the season. Drew suffered a season-ending right ankle fracture while sliding into home on July 20. There is no timetable on when he will return. "We are going to determine how hard we push him from where he is at now and how quickly," Gibson said. "We don't want him to come back and then go back on the disabled list. We want to make sure he is right, comfortable and able to do what he has to do to be a consistent contributor." ... Following the game, the Brewers assigned infielder Brooks Conrad to Triple-A Nashville. Conrad batted just .204 this spring, but hit four home runs. The move allows Travis Ishikawa to become the reserve first baseman.