Cubs starter Tsuyoshi Wada (2-1) was coasting until he was chased in the seventh, when he allowed consecutive home runs to Rickie Weeks and Martin Maldonado. Wada allowed two runs on five hits in 6 2-3 innings. He struck out five and walked one.
Hector Rondon pitched a scoreless ninth for his 16th save in 20 tries.
Lohse (11-7) allowed four runs on seven hits in three innings, and tweaked his right ankle during at at-bat.
It was his shortest outing of the season and marked the second time in his last three starts that he failed to pitch into the fifth inning.
Coghlan hit Lohse's second pitch of the game off the center-field wall for a double and scored on Rizzo's sacrifice fly. Castro drove in Baez on a single to give the Cubs a 2-0 lead in the first inning.
Baez and Rizzo sent the crowd buzzing in the third inning with back-to-back shots. Baez hit a tape-measure shot onto Waveland Ave. leading off the inning and Rizzo hit Lohse's next pitch into the right-field basket for a 4-0 advantage. It was Baez's fourth of the season and Rizzo's 27th.
After not hitting a home run since July 22nd, Rizzo has hit home runs in consecutive games.
Brewers: After soreness persisted in his right elbow, INF Jeff Bianchi had a second opinion in Arizona that confirmed the original diagnosis. He has sat out 25 games on the disabled list.
Cubs: LHP Felix Doubront (strained calf) allowed three runs on four hits and two walks in four innings on Tuesday night. The recent arrival could join the parent club after one more start for Triple-A Iowa this week. RHP Brian Schlitter (inflamed shoulder) began his rehabilitation stint at the club's spring training complex in Mesa, Ariz.
UP NEXT: Brewers RHP Mike Fiers (1-1, 1.80) will oppose Cubs RHP Edwin Jackson (6-12, 5.61) in the series finale Thursday.