Giants 4, Padres 2

Giants 4, Padres 2: Gregor Blanco snapped an eighth-inning tie with an RBI ground-rule double and Madison Bumgarner worked seven strong frames as visiting San Francisco snapped a four-game slide.

Blanco recorded three hits, Pablo Sandoval homered and Buster Posey drove in an insurance run in the eighth in support of Bumgarner (10-5), who allowed two runs and four hits. Sandy Rosario tossed a scoreless eighth and Sergio Romo set San Diego down in order in the ninth for his 21st save.

Luke Gregerson (4-5) surrendered three hits, including Blanco’s go-ahead double and Posey’s run-scoring single, in his only inning of work. Carlos Quentin and Chris Denorfia combined for four of the Padres’ five hits as the club returned to the basement in the National League West.

San Diego jumped ahead 2-0 in the opening frame on Quentin’s RBI double off the wall in left-center field and Kyle Blanks’ bases-loaded groundout. Padres starter Jason Marquis stranded runners in scoring position over the next two innings before surrendering Sandoval’s solo shot to lead off the fourth.

Kensuke Tanaka came through with his first major-league RBI on a single up the middle in the sixth to knot the game at 2-2 and end Marquis’ night. Blanco’s slicing liner in the eighth went over the head of Quentin in left and one-hopped the fence to plate Tanaka, and Posey ripped a single into shallow left to give the Giants a two-run cushion.

GAME NOTEBOOK: The Giants won their first series opener in eight tries. … The Padres have dropped 12 of their last 13 games. … Bumgarner has allowed three runs or fewer in each of his last seven starts, going 6-1 with a 2.30 ERA.