HOUSTON -- Mike Rivera had taken some good-natured ribbing around the Milwaukee clubhouse after going hitless in nine at-bats in July.
Prince Fielder hit his 27th home run and Ryan Braun knocked in two runs for the Brewers, who finished with 14 hits. Casey McGehee, Bill Hall and Felipe Lopez added RBI for Milwaukee.
The Brewers led 3-0 when Houston starter Mike Hampton (7-9) left after two innings with a sprained right knee. Ivan Rodriguez doubled and scored in the second inning off Manny Parra (7-8).
Yorman Bazardo, whose Triple-A contract was purchased by the Astros after Friday night's game, relieved Hampton and got into immediate trouble, giving up a leadoff double to McGehee and walks to Hall and J.J. Hardy.
Rivera cleared the bases with a double to the left-field corner. He had two hits in the game -- his first since June 27.
"We were joking about that I didn't get any hits in July," said Rivera, who got a rare start to give Jason Kendall a day off. "I haven't had that many chances to get RBI lately. It feels great to contribute."
Houston manager Cecil Cooper said before the game that he didn't think Bazardo was ready to start. He had just pitched for Triple-A Round Rock on Wednesday.
"I take the heat on that," Cooper said. "I asked him before the game and he said he didn't think he could pitch. He went out and sucked it up anyway. It was pretty tough for him."
After Rivera's hit, Parra bunted to the third-base side. Bazardo scooped it up and threw wildly to first and Rivera scored for a 7-1 lead. Bazardo was charged with an error.
"Obviously, my stuff wasn't there," Bazardo said. "I was just trying to work to get out of the inning."
Fielder added an RBI single before Bazardo got the last out and Wesley Wright relieved for the fourth.
The Astros' bullpen gave up nine runs over the final seven innings and the Brewers reached their highest run total since a 14-12 win at Cleveland on June 16.
"We had some key hits," said Milwaukee manager Ken Macha. "We got some big hits with guys on."
Carlos Lee hit his 300th home run, becoming the first Panama-born player to reach the milestone. The Astros are the first team in history to have three players reach 300 home runs in the same season. Rodriguez hit his 300th homer against the Cubs in Chicago on May 17 and Lance Berkman reached the mark in Arizona on June 13.
"It was another accomplishment in my career," Lee said of the homer. "It would've been a lot nicer if we were celebrating a win right now."
Parra struck out one hitter in each of the first four innings. Houston loaded the bases with no outs in the fifth and Wright scored when Hunter Pence grounded into a fielder's choice. Lee then grounded into a double play and fans started filing for the exits.
"The best thing you can do in that situation is just pound the strike zone," said Parra, who threw 107 pitches. "I thought I threw the ball pretty well."
Fielder doubled off Wright leading off the sixth and scored on Hall's single to center.
The Astros strung together three singles in their half of the sixth to make it 9-3. Parra walked Geoff Blum to load the bases and Claudio Vargas relieved.
Jason Michaels scored on Kaz Matsui's sacrifice fly, but Vargas struck out Jeff Keppinger to stop the rally.
Fielder hit a two-run homer to left in the seventh against Tim Byrdak to make it 11-4. Lee answered with a solo shot in the bottom half against Vargas.
Alberto Arias pitched the ninth for the Astros and gave up Lopez's RBI double.
Hampton has allowed 26 runs in first innings this season. ... Astros RHP LaTroy Hawkins threw a bullpen session on Saturday. Hawkins has been on the disabled list since July 28 due to shingles. He'll throw a simulated game on Monday. ... Fielder had three RBI in a game for the first time since July 16. ... Parra has won his last four decisions. The Brewers improved to 7-12 in games Parra has started this season.