PHOENIX -- Sometimes the math just doesn't matter. San Francisco catcher Buster Posey snapped a skid with runners in scoring position while breaking Daniel Hudson's hold on right-handed hitters at the same time.

Posey's two-out, two-run double with the bases loaded broke a tie in the ninth inning and lifted the Giants to a 5-3 victory over the Arizona Diamondbacks on Saturday night at Chase Field.

Posey was hitting .143 with runners in scoring position and righties were 0-for-27 against Hudson after Matt Duffy grounded into a forceout at the plate for the second out of the ninth.

"That's the goal, to be in the moment and focus on the moment as much as you can, but that's part of the challenge at times, to be able to do that," Posey said about ignoring the numbers.

Pinch-hitter Conor Gillaspie singled with out in the ninth against Hudson (1-1) before Denard Span was hit by a pitch on the left leg and Joe Panik walked. Duffy hit a broken-bat grounder to first for a force at the plate to bring up Posey, whose ground-rule double bounced into the pool area in right-center field.

Posey is a career .313 hitters with runners in scoring position.

"They usually get back to who they are, the numbers," Giants manager Bruce Bochy said. "It usually balances out, and good things are going to happen. That was a huge hit off a tough pitcher."

Hunter Pence hit a two-run homer, the 200th home run of his career, and Span had four hits and scored twice. Jake Peavy gave up one run and three his in six innings in his most efficient start of the season, although he did not get a decision.

The Giants (21-18) have their first four-game winning streak of the season and the Diamondbacks (17-22) lost their fourth straight after a five-game winning streak.

Chris Owings had two hits, scored a run and drove in one for Arizona, which is 5-15 at home. Jean Segura had his career-tying 11-game hitting streak snapped.

Cory Gearrin gave up a one-out single in the ninth for his first career save. Closer Santiago Casilla had worked the previous three days.

Hunter Strickland (1-0) got the victory despite giving up the tying run when Paul Goldschmidt and Chris Herrmann singled and pinch-hitter Phil Gosselin hit a sacrifice fly in the eighth.

Pence's homer, which came just as the roof at Chase Field was being opened at the start of the fourth inning, bounced off the top of the left field fence to give the Giants a 3-1 lead in the third.

"They opened the roof that inning. ... I didn't think it had a chance to go out," Bochy said. "It just flew. I think it surprised everybody."

Pence is 11-for-24 with four homers and nine RBIs in his career against Arizona left-hander Patrick Corbin, who went 6 1/3 innings but did not get a decision.

"I thought it was a good pitch," Corbin said. "He seems to do that off me."

Pence has 69 homers with San Francisco, 103 with Houston and 28 with Philadelphia.

"I'm very appreciative I had a chance to reach that mark. It's cool," Pence said. "It's best served in a winning effort. A pretty good ballgame all around from our guys."

Peavy gave up one run and three hits in six innings. He struck out five and walked two while throwing only two pitches as fast as 89 mph.

"The last start I threw 113 pitches about as hard as I could throw all of them," said Peavy, who entered with an 8.47 ERA. "Today was the polar opposite. I don't know if I threw one and let it all hang out. The problem hasn't been stuff, it's been execution."

NOTES: Arizona RF David Peralta (wrist) missed his seventh straight start and manager Chip Hale said a stay on the disabled list remains a possibility. "We have a date that we've decided that we are going to go to," Hale said. "It's coming up. Right now, it could go either way." ... San Francisco LF Angel Pagan (hamstring) missed 11 days but was not placed on the disabled list before returning to action Friday. ... Giants RHP Johnny Cueto received his 2015 World Series ring before the game. Acquired by Kansas City at the trade deadline, Cueto was 2-1 with a 5.40 ERA in four postseason appearances for the Royals. ... Hale attended his daughter's high school graduation in Tucson on Saturday morning before arriving at Chase Field about three hours before the start of the game. ... The Giants are 17-7 in games started by LHP Madison Bumgarner (5-3), RHP Johnny Cueto (7-1) and RHP Jeff Samardzija this season. They all are scheduled to start in a three-game series that begins Tuesday in San Diego.