Norichika Aoki capped a four-run eighth with a two-run single and the Milwaukee Brewers took advantage of a sloppy inning from the Giants to win, 6-1, in the third installment of a four-game series.
It could be a costly victory for the Brewers. Second baseman Rickie Weeks grabbed his left hamstring while grounding out in the eighth inning and was helped off the field. Brewers manager Ron Roenicke said Weeks suffered a strained hamstring and it's possible he could go on the disabled list.
Khris Davis homered and pinch-hitter Martin Maldonado singled in a run in the ninth, but the big play came in the eighth on Madison Bumgarner's error.
Davis singled and Yuniesky Betancourt doubled to put two runners in scoring position. Jeff Bianchi legged out an infield hit for a run when shortstop Brandon Crawford double-clutched before making a throw on a routine play.
Pinch-hitter Logan Schafer bunted, but Bumgarner's low throw to third base deflected off the glove of Pablo Sandoval and went through his legs into foul territory. Betancourt scampered home and Bianchi went to third. After Weeks grounded out, Santiago Casilla gave up Aoki's two-run hit to center for a 4-1 margin.
Marco Estrada, who was activated off the disabled list, allowed one hit over the first five innings for the Brewers. Bumgarner (11-7) gave up five hits and four runs in seven-plus frames.
The Giants had only three hits and lost for the fourth time in five games. They gained a 1-0 lead in the seventh, but should have had more runs if not for Davis' scintillating catch in left.
"We played really good defensively. Timely hitting, we got some breaks. Those are good wins for us because it doesn't happen very often," Roenicke said.
Crawford walked and Brandon Belt singled. The runners moved up on a wild pitch before one run scored on Buster Posey's sacrifice liner which Davis made a diving catch to prevent a second run from scoring.
"That was a game-changer. We still got a run out of it. That hurt us probably as much as anything too. It was a different ball game," Giants manager Bruce Bochy said.
Davis homered to left off Barry Zito with one out in the ninth, and Maldonado's hit to right plated Bianchi.
Alfredo Figaro (2-3) threw two innings to get the win.
There was more great defense by the Brewers, specifically from center fielder Carlos Gomez. He robbed Posey of a hit by crashing into the wall in left- center in the first, then made a leaping grab in the fifth to take a hit away from Sandoval.
The Brewers opened a spot for Estrada by optioning second baseman Scooter Gennett to Triple-A Nashville ... Bumgarner had a nine-start streak broken in which he allowed two earned runs or fewer ... The Giants have gone 11 consecutive home games without hitting a home run.