LOS ANGELES -- Scott Van Slyke has bounced between the Dodgers and the minors five times this season, even smiling whenever manager Don Mattingly approached him with the news that he would be going back down again.
"It's been my goal the whole year just to contribute," he said, having been called up from Triple-A Albuquerque on Sept. 1.
Van Slyke found himself in a celebratory dog pile after triggering the Dodgers' seventh walk-off victory of the season. As he rounded the bases, he knew what awaited him.
"I'm about to get my jersey torn off," he said of the team's ritual.
"I was just looking for something to hit hard," Van Slyke said. "It was a good changeup down."
It was the Dodgers' fifth consecutive victory against the D-Backs. Los Angeles reduced its magic number in the NL West race to six, and leads the division by 13 games over Arizona with 18 to play.
"Everybody is excited about it," Van Slyke said. "We're on a roll and we want to continue winning games. I think our attitude will continue to be the same after we clinch."
Los Angeles hit six home runs, including three by Juan Uribe, in winning the series opener on Monday.
Chris Withrow (3-0) got the victory, striking out four in 1 1/3 innings. The bullpen allowed only one hit in five scoreless innings.
Collmenter gave up two runs and three hits.
The Dodgers had the go-ahead run on third with two outs in the 10th.
Adrian Gonzalez singled and was replaced by pinch-runner Dee Gordon, who stole second. Andre Ethier was intentionally walked before Collmenter uncorked a wild pitch, allowing Gordon to take third. Ethier moved up to second when the ball sailed to the backstop. Juan Uribe struck out swinging to end the threat one night after he hit three home runs.
After Arizona took a 3-2 lead in the top of the fifth, the Dodgers tied the game in the bottom of the inning on Ethier's RBI double that scored Hanley Ramirez, who walked with two outs.
"They've got a good team, from their lineup to their pitching," Arizona starter Trevor Cahill said. "There's a lot of veterans there who have done it before and put up those kind of numbers, and now they've got younger guys like [Yasiel] Puig."
The Diamondbacks trailed 2-1 in the fourth on Miguel Montero's RBI single.
Los Angeles led 2-0 in the second on fielder's choice groundouts by Volquez and Yasiel Puig.
Volquez gave up three runs and four hits in six innings of his second start and third appearance as a Dodger since signing on Aug. 30. He struck out five and walked one.
"He's throwing harder now, in the mid-90s instead of the low 90s, and he's keeping guys off balance with that changeup and curveball," said Adam Eaton, who went hitless in five at-bats. "That's the name of the game, and I think he did a good job of that. He was bearing down when there were guys in scoring position."
Cahill allowed three runs and four hits in six innings, struck out two and walked four.
The Dodgers improved to 9-5 in extra-inning games, including 4-1 at home. ... The D-Backs dropped to 16-7 in extra innings, including 10-4 on the road. ... Arizona leads the majors with 23 extra-inning games played and has already set an NL record with 75 extra innings this season. ... Mattingly said he's increasingly optimistic that OF Matt Kemp could return this season. Kemp has been rehabbing a sprained left ankle, although he was slowed recently by a strained hamstring. ... D-Backs 1B Paul Goldschmidt went 2 for 5 with a double and a run scored on his 26th birthday. He's hitting .344 against the Dodgers this season.