Starter Clayton Richard (2-0) and the Cubs' bullpen held off the Brewers until the ninth, when Rondon allowed the first two runners to reach base with his team leading 4-1.
Ryan Braun scored on a groundout with one out, and Hernan Perez drove in another run with a two-out single. Rondon then got pinch-hitter Logan Schafer to line out sharply to center for his 16th save.
Bryant left in the fifth after sliding headfirst into second and appearing to get tagged on the helmet by shortstop Jean Segura.