Milwaukee used all relievers to accommodate their pitching schedules, with each tossing a single inning. Closer John Axford yielded the first run, allowing back-to-back doubles to the Rockies' Wilin Rosario and Charlie Blackmon to make it 1-0.
Lefty Michael Gonzalez gave up two more runs in the second. Henry Wrigley raised his Cactus League average to .400 with a single to center, then advanced to second when center fielder Carlos Gomez let the ball get past him for an error. Eric Young Jr. followed with a perfect bunt single to the pitcher, moving Wrigley to third, and Carlos Gonzalez plated them both with a stand-up double down the left-field line.
In the fifth, Carlos Gonzalez launched a two-out solo shot onto the right-field berm -- a no-doubter for his first round-tripper of the spring. He also hit a double to left in the third.
"That's when you become a good hitter, when you use the whole field and you use it for power," Gonzalez said. "So today was a good day. Even when I struck out my first at bat, I was hitting the ball good. It was lefty-lefty.
"That's what you want from the beginning of the year, and hopefully you can continue to get better and make progress. That's how you're going to continue to get back to the level that you wanted to start."
The Rockies got two solid innings from Rule 5 Draft choice Rosenbaum, as the starter threw two scoreless innings for the second time this spring. As per Rule 5 rules, Rosenbaum must be on the Rockies' Opening Day roster or be offered back to the Nationals for $25,000.
Volstad followed Rosenbaum, resuming his bid for the Rockies' fifth-starter slot. Volstad pitched three innings, giving up a run in the fourth after a leadoff triple to Jean Segura and a run-scoring grounder to first from Logan Schafer.
The Rockies staged an unusual double play in the top of the sixth, as Segura singled to right for his second hit and then was caught off first by shortstop Reid Brignac. First baseman Michael Cuddyer then caught Norichika Aoki, who thought there were three outs, at second to end the inning on a 9-6-3-4 double play.
Ben Paulsen's RBI single scored Corey Dickerson in the eighth to give the Rockies a 5-1 lead, and then the Brewers' Robinzon Diaz drove in Khris Davis with a single in the ninth to make it 5-2.
Up next: The Brewers play host to the Angels at 2:05 p.m. CT, a game that can be heard live on Gameday Audio. With World Baseball Classic participants set to leave the club Sunday, the game will be their last chance to either impress manager Ron Roenicke. The Brewers have 13 players, representing seven different countries, competing in the Classic. Among the notable Brewers competing are Ryan Braun (USA), Jonathan Lucroy (USA), Yovani Gallardo (Mexico) and Axford (Canada).