Giants 6, Brewers 4: Buster Posey homered and had three RBIs for the second straight night to power San Francisco past host Milwaukee.

Joaquin Arias clubbed a two-run homer, the first of his career, and Matt Cain labored through seven innings to win his third straight start.

Cain (4-2) allowed four runs on 11 hits while striking out eight in helping the Giants win for the fifth time in six games.

Slumping Rickie Weeks had a two-run double and Ryan Braun extended his hitting streak to 11 games for Milwaukee, which fell a season-worst nine games below .500 with its sixth defeat in the last seven games.

Arias' two-run shot in the fourth made it 4-0, and Posey's two-run blast off Brewers starter Shaun Marcum in the sixth put the Giants ahead 6-2.

Norichika Aoki and Braun had RBI hits in the seventh to bring Milwaukee within 6-4, but Sergio Romo pitched a perfect eighth before closer Santiago Casilla nailed it down for his 11th save.

Marcum (2-3) was charged with six runs on five hits in six innings. Aoki, Aramis Ramirez and Jonathan Lucroy each had two hits for the Brewers.

GAME NOTEBOOK: Braun was back in the lineup after leaving Monday's game in extra innings with right groin tightness. He extended his RBI streak to five games. ... Posey has driven in 10 runs during a six-game RBI streak. ... Brewers 1B Mat Gamel underwent successful knee surgery to repair his torn anterior cruciate ligament. ... Giants CF Angel Pagan, who missed Monday's game with a stomach ailment, drove in a run with a sacrifice fly but had his 11-game hitting streak snapped. Teammate Melky Cabrera extended his hitting streak to six games. ... Weeks drove in his first run since April 24.