Giants 7, Rockies 3: Buster Posey homered and Matt Cain settled in after a shaky start as San Francisco won the rubber game of the three-game series against visiting Colorado.

Cain (4-2) walked two of the first three batters he faced and allowed Michael Cuddyer’s two-run double in the first before tossing four shutout innings. Cain won his fourth straight decision despite issuing a season-high five walks.

Posey hit a leadoff homer in the second off Jon Garland (3-6), and the Giants pulled even in the fourth when Brandon Belt scored from third on Brandon Crawford’s fielder’s choice grounder. Posey went 2-for-4 and extended his hitting streak to 10 games.

The Giants moved ahead 4-2 in the fifth when Belt and Andres Torres hit back-to-back RBI doubles off Garland, and Hunter Pence added to the lead in the sixth with a two-run double off Edgmer Escalona. Garland was charged with five runs (two earned) over five frames.

After homering in three straight games, Rockies left fielder Carlos Gonzalez went 0-for-5 with three strikeouts. Colorado, which lost Saturday’s game 6-5 on Angel Pagan’s walk-off, inside-the-park homer in the 10th inning, dropped to 22-8 when scoring first.

GAME NOTEBOOK: Cuddyer left the game with a bruised right forearm after being hit by a pitch in the sixth inning. X-rays were negative. … Pagan missed the game due to a mild hamstring strain. … Giants RHP Santiago Casilla will undergo surgery this week to have a cyst removed from his right knee.