For the third time in four days, the teams switched places atop the division standings, with San Francisco regaining a half-game lead over Los Angeles.
By contrast, Bumgarner was immovable. In an effort that recalled the eight-inning shutout Bumgarner pitched against Texas in Game 4 of the 2010 World Series, he allowed four hits, walked none and struck out 10 while allowing just two Dodgers to reach scoring position.
Bumgarner (14-7) bested Clayton Kershaw (11-7), the Dodgers ace and reigning NL Cy Young Award winner, who also struck out 10 in eight innings while surrendering both Giants runs and six hits.
Asked whether facing pitchers of Kershaw's class motivates him to elevate his performance, Bumgarner replied, "I don't know. Sometimes, I guess, sometimes no. You better pitch better if you want to win."
It's clear by now that winning is what Bumgarner's all about.
"He's fun to watch," Giants manager Bruce Bochy said. "He's like all good pitchers. He competes out there. He's pitching to win."
Maybe that's self-evident. But some pitchers shrink from challenges. Bumgarner thrives on them, as he did in the sixth inning. Kershaw led off the Dodgers' half of the sixth with his second single and was forced out by Shane Victorino, who promptly stole second and third. The latter theft came on a pitch in the dirt that ran the count on Matt Kemp to 3-2 with two outs. Bumgarner ended the drama by fanning Kemp on a low slider, then bellowed in an unusual display of emotion.
"That was a big strikeout for me," Bumgarner said. "That was a big part of the game right there. I got a little excited; the fans were screaming and yelling."
Kershaw displayed similar passion. His diving catch at the first-base line of Gregor Blanco's popped-up bunt attempt in the third inning reflected that. The left-hander lapsed only briefly, as San Francisco's top three hitters in the batting order -- Angel Pagan, Marco Scutaro and Pablo Sandoval -- collaborated to manufacture runs in the first and sixth innings.
"Anytime you play the Giants, it's a big game, especially right now in the middle of a playoff race," Kershaw said. "Every game is big at this point, but losing [stinks] no matter what. Tonight didn't feel any better."
Bumgarner sustained his excellence while throwing a season-high 123 pitches and possessed enough energy to finish his outing by striking out pinch-hitter Juan Uribe and Shane Victorino.
"He's a big, strong boy," Bochy said of Bumgarner, whose 61 strikeouts since the All-Star break lead the NL. "I wasn't concerned with the pitch count."
During the rare instances that concern rose, Bumgarner received defensive help. Catcher Buster Posey threw out two would-be basestealers. Before Bumgarner struck out Kemp to end the sixth inning, right fielder Hunter Pence made a deft, diving catch of Mark Ellis' line drive. Second baseman Scutaro did a nice imitation of Freddy Sanchez in the 2010 Series by leaping to snare A.J. Ellis' liner to open the eighth. Bochy said that had Scutaro not made that grab, Bumgarner probably would have been removed at that juncture.
Scutaro felt mostly certain that he could make the play. "I was in good position," he said. "Sometimes line drives go up or they move, but that one stayed kind of straight."
Sergio Romo needed one strike to secure his sixth save when Hanley Ramirez reached the left-field pavilion with his 19th home run. This echoed July 27, when Ramirez's two-run, 10th-inning long ball beat Romo and launched a three-game Dodgers sweep at AT&T Park.
But Javier Lopez denied the Dodgers another series-opening triumph by coaxing Andre Ethier's game-ending grounder to first base.
"Closer by committee is not an ideal thing," said Lopez, who recorded his second save. "But it's something that works for us."