Padres 6, Giants 4: Rene Rivera homered and drove in a career-high five RBIs as visiting San Diego edged San Francisco in the opener of a three-game series.

Rivera’s three-run homer in the fifth off Madison Bumgarner (2-3) put the Padres ahead to stay. Alexi Amarista and Tommy Medica each scored twice as San Diego improved to 3-1 against the Giants this season.

Tyson Ross (3-3) allowed four runs and eight hits in 5 1/3 innings to help end San Francisco’s four-game winning streak. Three relievers bridged the gap to Huston Street, who struck out two in a perfect ninth for his 10th consecutive save this season.

Rivera stroked a two-run double down the third-base line in the fourth to open the scoring and the Giants tallied three times in the bottom of the inning on Hunter Pence’s run-scoring triple and Michael Morse’s two-run ground single. Medica singled with one out in the fifth and Amarista walked before Rivera launched his blast over the left-center field to give San Diego a 5-3 lead.

Brandon Hicks homered to center in the bottom of the fifth to pull San Francisco within one and flew out to the warning track in left-center with the bases loaded in the sixth. The Padres added a run in the ninth when Will Venable doubled and moved around to score on two grounders.

GAME NOTEBOOK: Bumgarner allowed five runs (four earned) and seven hits in five innings. … Padres 2B Jedd Gyorko was placed on the three-game paternity list with his wife giving birth to twin boys and Medica replaced him on the roster. … Giants manager Bruce Bochy (third inning) and Padres manager Bud Black (fourth) challenged calls by first base umpire Angel Hernandez and were proven correct in their challenges.