The NL Central-champion Brewers are a game ahead of Arizona for the second- best record in the National League. The Diamondbacks, however, own the tiebreaker should the teams finish with identical records.
Milwaukee won for the 10th time in 14 tries with Tuesday's 6-4 victory over the Pirates, as Prince Fielder knocked the cover off the ball with three homers and five RBI.
"Great ballgame for him," Brewers manager Ron Roenicke said about Fielder, who may test free agency after this season. "He can carry a team."
Rickie Weeks also homered and LaTroy Hawkins picked up the win with a scoreless inning of relief. John Axford posted his 46th save in the ninth and starter Randy Wolf was banged around for four runs and nine hits over 5 2/3 innings.
Zack Greinke will take the mound for the Brewers and is 15-6 with a 3.86 ERA in 27 starts. He did not record a decision in a 6-4 win over Florida on Saturday and was reached for five runs and nine hits in five innings. The righty lost to Pittsburgh on Aug. 22, but is 3-1 with a lofty 5.68 ERA in four career starts against the Pirates.
Greinke has been superb at home, going 10-0 in 14 starts at Miller Park.
Pirates reliever Jared Hughes gave up Fielder's third home run in the seventh inning to take the loss. Starter Ross Ohlendorf allowed four runs on five hits and three walks through five innings.
Alex Presley had two hits and an RBI for the Pirates, who had won four of six contests.
Pittsburgh, which hasn't enjoyed a winning season since 1992, will send Jeff Locke to the mound tonight for his fourth career starts. The rookie lefty is 0-2 with a 4.97 ERA in his first three starts and did not record a decision in Friday's 4-3 win versus Cincinnati.
Locke held the Reds to a run and six hits in 4 2/3 innings. He lost his first two major league starts against the Marlins and Dodgers.
Milwaukee is 11-3 against the Pirates this season, including a 7-1 mark at Miller Park. It had won 12 in a row as the host in this series before Monday's series-opening loss.
The Pirates are only 4-37 in their previous 41 contests in Brew City.