Giants 4, Padres 1: Pablo Sandoval homered and Madison Bumgarner pitched into the eighth inning as the Giants won the rubber game of the series.

Bumgarner (4-1) became the Giants’ first four-game winner while giving up six hits with one walk and six strikeouts over 7 2/3 innings.

Santiago Casilla worked a scoreless ninth inning for his fourth save and second in as many games.

The Giants grabbed a 2-0 lead in the first inning on Melky Cabrera’s sacrifice fly and Sandoval’s fourth home run off Clayton Richard (1-3), who allowed four runs over seven innings.

Richard settled in and tossed four scoreless innings before Joaquin Arias hit a two-run triple with two outs in the bottom of the sixth, scoring Buster Posey and Brett Pill.

San Diego scored its lone run in the fifth when Chris Denorfia’s double scored Jason Bartlett, who led off the inning with an infield single.

Denorfia had two hits and is batting 9-for-19 (.474) in his career against Bumgarner, who has won four consecutive decisions after losing his first start.

GAME NOTEBOOK: Bumgarner has held opponents to two runs or less in his last nine starts at AT&T Park ... Richard, who allowed nine home runs in 99 2/3 innings last year, has allowed five in his first 25 innings this season …The Padres have been outscored 40-19 over the first three innings of their games this season …The Padres issued just two walks in the three-game series, both on Sunday … Sixteen of the Giants’ 22 games this season have been decided by three runs or fewer.