PHOENIX -- Madison Bumgarner wasn't his best on Thursday night, but the Giants ace did enough on the mound, and at the the plate, to help steer San Francisco to a victory at the beginning of a crucial stretch.
The left-hander tossed five innings of one-run ball and knocked in the go-ahead run against Zack Greinke, while the Giants' bats came alive late in an 8-1 win over the D-backs in the opener of a four-game series at Chase Field. San Francisco started a stretch of 13 consecutive games against postseason contenders on Thursday, including two from the NL West -- the D-backs, Astros, Pirates and Dodgers.
Although the Giants gained ground on the D-backs in the National League West, they remain five games behind the Dodgers, who took sole possession of first place with a win over the Brewers and Arizona's loss.
"Come with your best stuff, and these are the teams that we have to beat to make a push," said first baseman Austin Slater, who went 2-for-3 with two RBIs and three runs scored. "All of these teams are in front of us, and if we can gain ground on any of them, or all of them, that's what we're trying to do."
Bumgarner scattered seven hits, walked three and struck out five. He loaded the bases in the first and second innings but limited the D-backs to one run, which came on a one-out sacrifice fly by Eduardo Escobar in the second.
Although Bumgarner has gone deeper than six innings only three times in 11 starts this season, he has a 2.97 ERA. He stranded nine D-backs baserunners, seven of which were in scoring position, including seven in the first three innings.
"That's not the way I'd like to draw it up," Bumgarner said. "I'd like to be in there a lot longer than five innings and not have to work quite so hard. At the same time, those types of games are gratifying, to keep your team in it."
After Bumgarner's departure, San Francisco's bullpen combined for four scoreless innings and three hits allowed, with Ty Blach working the final two frames.
The Giants took a 2-1 lead in the fifth after Slater scored on a Bumgarner single to left field off Greinke, who allowed two runs on four hits over six innings.
Slater created another scoring opportunity in the seventh when he walked, advanced to second on an error and moved to third on a wild pitch. He scored on a Hunter Pence sacrifice fly to make it 3-1, before San Francisco padded its lead with a five-run eighth.

With Brandon Belt on the disabled list and Pablo Sandoval set to undergo season-ending hamstring surgery next week, Slater will need to play more first base, where he has played 17 games between Triple-A Sacramento and the Majors this season. He never played there in his four previous professional seasons, spending most of his time in the outfield.
"He's a pretty good hitter," Giants manager Bruce Bochy said. "He's getting a lot of playing time now and doing some good things. Here's a kid that we moved to first base. That's not an easy transition, although he played some first down there in Triple-A, but he's handling that well and he gives you good at-bats up there."

MOMENT THAT MATTERED
Big rally in eighth: The Giants sent 10 to the plate in the eighth, scoring five runs on six hits and an error. Slater had the big hit in the rally, a two-run single up the middle that was misplayed by D-backs center fielder A.J. Pollock, allowing a third run to score on the play and make it 7-1. Steven Duggar's RBI single to right capped the scoring. Four of the five runs were charged to Brad Ziegler, whom the D-backs acquired at the non-waiver Trade Deadline.
A key moment came before any runs had been scored with one out and the bases loaded. After pitching coach Mike Butcher made a visit to Ziegler, the Giants countered by pinch-hitting the left-handed-hitting Alen Hanson for Chase d'Arnaud. D-backs manager Torey Lovullo asked home-plate umpire Tony Randazzo if he could remove Ziegler. Typically, Lovullo would not be allowed because of Butcher's visit, which was what Randazzo told him. However, due to Rule 5.10 (I), Lovullo should have been allowed to go to the mound to remove Ziegler if he wanted.
"There's a caveat rule that says when there's a trip to the pitcher and then the guy leaves the mound and the offensive team then substitutes, it is then permissible by rule to then go to the mound to remove the pitcher," crew chief Bill Welke said.
Hanson drove in the first of five San Francisco runs that inning with a single.

SOUND SMART
Bumgarner has a 2.81 ERA in 105 2/3 career innings at Chase Field, which is the lowest in ballpark history (min. 15 starts). Hall of Famer and former D-backs great Randy Johnson is second at 2.96.

YOU GOTTA SEE THIS
After homering in the top of the first inning, Giants third baseman Evan Longoria protected a 1-0 lead with a defensive gem in the bottom of the frame. With the bases loaded and one out, Longoria made a diving play to his left to rob Steven Souza Jr. of a hit and save at least one run. Bumgarner then escaped the inning unscathed. More >

UP NEXT
The Giants send Chris Stratton to the mound to continue their series against the D-backs on Friday at 6:40 p.m. PT. Stratton is making his first start since July 3 after he was recalled from Triple-A Sacramento on July 26. The right-hander made one relief appearance since his return, on July 26, when he allowed three runs in 1 1/3 innings against the Brewers. Patrick Corbin is slated to start for Arizona.