PHOENIX -- Patrick Corbin isn't an automatic win anymore, and that's just more bad news for the Arizona Diamondbacks.
For a long time, Arizona won just about every time the young left-hander was on the mound.
But the long season seems to be taking its toll.
Corbin (13-5), pitching on two extra days' rest, allowed five runs in six innings and the Diamondbacks lost to the San Francisco Giants 8-2 on Sunday. The Giants took two of three in the series as Corbin fell to 1-4 in his last seven starts.
"I felt all right, I just wasn't really locating anything and left some pitches up," he said. "I had a chance to get out of it in the one inning where they scored three but left the breaking ball up. I just wasn't executing my pitches that well today."
In his last two outings, Corbin has allowed 13 earned runs on 16 hits. Still, Arizona manager Kirk Gibson said Corbin pitched well enough to win.
"You can't pin the loss on Patrick Corbin today," Gibson said. "We didn't pitch very well after that. We didn't have a very good approach on these guys and they hit some good pitches, to be fair. They pitched well against us."
Yusmeiro Petit rarely pitched so well in his days with the Diamondbacks.
An older, wiser version of the former Arizona right-hander was on the mound against his old team on Sunday, and for the second straight start since he was called up from the minors, Petit was in control.
He struck out a career-high 10, Hector Sanchez drove in three runs and the San Francisco Giants beat Arizona 8-2 to take two of three from the Diamondbacks.
Hunter Pence homered, doubled and singled, driving in two runs and scoring three times as the Giants improved to 10-5 against Arizona this season.
But the story for San Francisco was Petit.
"I'm not going to say surprised, I'm going to say I'm happy for him," Pence said. "He's just gets his work done. He's done everything the right way. He's a good guy to have around the clubhouse. He's positive. He has tremendous command, he's got a couple of off-speed pitches to keep them honest, and it's been fun playing behind him."
Petit (2-0), who pitched for the Diamondbacks from 2007-09, went six-plus innings, allowing two runs on seven hits in his first career start against Arizona. He also singled in a run, his second career RBI.
He was making his second start since being called up from Triple-A Fresno. He gave up two runs on six hits in six innings in a 5-3 win at Colorado on Tuesday.
Petit's previous career high in strikeouts was eight on three occasions, most recently July 29, 2009, while pitching for Arizona against Philadelphia. He said he's a "completely different" pitcher than he was in those days.
"Experience," he said with a teammate serving as translator. "Before I wasn't consistent with what I was doing."
Gibson said Petit "is a little bit more mature" than he was in his days with the Diamondbacks.
"He had a good plan today and he hit his spots," Gibson said. "When you hit your spots with that much regularity it makes it tough."
San Francisco won its fourth consecutive series over the Diamondbacks overall and fifth series in a row in Arizona. The Diamondbacks last won a series at home against the Giants April 6-8, 2012.
San Francisco scored three times with two outs in the fourth inning.
Buster Posey led off with a single, then Pence doubled to put runners at second and third. Pablo Sandoval flew out to right and Brett Pill grounded out to third and it looked as if Corbin might escape. But Sanchez doubled to left-center to bring both runners home and make it 3-1. Gregor Blanco's infield single put runners at first and third, then Petit's single to right put the Giants up 4-1. It was Petit's fourth career hit in 69 at-bats.
Pence's opposite-field home run on Corbin's full-count pitch with two outs in the fifth boosted the lead to 5-1.
Petit left after giving up a leadoff single to A.J. Pollock in the seventh. Left-hander Jose Mijares got Gerardo Parra to fly out, then struck out pinch-hitter Tony Campana. Willie Bloomquist singled to put runners at first and second, then Adam Eaton's RBI single cut the lead to 5-2. Right-hander Santiago Casilla relieved Mijares and, on the first pitch, Paul Goldschmidt flew out to center to end the inning.
Posey doubled in two runs off and Pence had an RBI single off Heath Bell in the ninth.
NOTES: The Giants activated 2B Tony Abreu off the 15-day DL. Abreu missed 31 games with bursitis in his left knee. ... The Diamondbacks recalled two relievers from Triple-A Reno, right-hander David Hernandez and left-hander Tony Sipp. ... The Diamondbacks open a three-game series against Toronto on Monday night, with right-hander Brandon McCarthy (3-8, 5.03 ERA) going for Arizona and right-hander Esmil Rogers (3-7, 5.03) on the mound for the Blue Jays. It's the Diamondbacks' final interleague series of the season. ... San Francisco goes to San Diego for a three-game series, with Barry Zito (4-10, 5.81) starting for the Giants and Ian Kennedy (5-9, 5.10) for the Padres. ... Arizona acquired minor league RH reliever Matt Langwell from Cleveland to complete the Jason Kubel trade to the Indians.