Prince Fielder hit three home runs for the breaking two-run blast in the 4 victory over the Pirates.
Fielder had a pair of two-run homers and a solo shot as the Brewers won for the 10th time in 14 games.
"Great ballgame for him," Brewers manager Ron Roenicke said about Fielder. "He can carry a team."
With wins by both the Brewers and Diamondbacks on Tuesday, Milwaukee still holds a one-game lead for home field advantage for the first round of the playoffs. Arizona holds the tie breaker entering the final game of the season.
John Axford tossed a perfect ninth to earn his 46th save of the year.
Jared Hughes (0-1) gave up Fielder's third home run in the seventh inning to take the loss. Ross Ohlendorf allowed four runs on five hits and three walks through a five-inning start for Pittsburgh.
Alex Presley had two hits and an RBI for the Pirates, losers in two of their past three contests.
Neil Walker led off the second inning with a ground-rule double over the right field wall and crossed the plate two batters later on Matt Pagnozzi's bloop single to shallow right.
Fielder and Rickie Weeks hit back-to-back, mammoth solo home runs in the third inning to put the Brewers ahead 2-1. Fielder's blast went an estimated 453 feet into the seats in right-center field and Weeks' shot bounced high off the glass of the luxury seats in left for an estimated 470 feet.
After Ronny Cedeno's ground-rule double in the fifth, Ohlendorf faked a bunt and then pulled his bat back and slapped a base hit up the middle to score Cedeno. Ohlendorf later came home on a Josh Harrison single to give Pittsburgh a 3-2 lead.
The Brewers took the lead right back in the bottom half of the fifth on a Fielder two-run homer to dead center field. Braun walked prior to Fielder's 37th home run of the year.
But Presley's bases-loaded walk in the sixth pushed Walker across the plate to tie the game at four.
With a runner on first in the seventh, Fielder pulled a ball over the right- field wall for his third home run of the game, putting the Brewers ahead for good.
"That guy can hit homers and he swings with such bad intentions. When he gets lasered in, I don't know how you can pitch to him," Pirates manager Clint Hurdle said about Fielder.
Fielder and Weeks' homers in the third inning was the seventh time the Brewers hit back-to-back home runs this season...It was Fielder's 22nd career multi home run game...The Brewers improved to 56-24 at home this season...The Pirates fell to 36-44 on the road...Milwaukee is 11-3 against Pittsburgh this season, including a 7-1 mark at Miller Park.