OAKLAND, Calif. -- The San Francisco Giants lost their third straight one-run game Friday night, falling 5-4 to the Oakland A's and moving to the brink of elimination from the playoff race.

The defending World Series champions remained eight games behind the Los Angeles Dodgers in the National League West, but their slim wild-card hopes died at the O.co Coliseum, and their elimination number in the division fell to two.

"The one-run games are killing us right now," Giants manager Bruce Bochy said. "We lost a couple tough ones in San Diego and then came up short tonight. Had some chances there, but it's caught up with us, these one-run losses."

Center fielder Billy Burns hit a two-run homer, designated hitter Billy Butler had a solo shot and right-hander Sonny Gray pitched six solid innings for the A's.

The A's were swept by San Francisco in a three-game series in July, but they beat the Giants for the sixth straight time overall in Oakland.

Gray (14-7) had one of his best starts in what has been a rough month of September. Going into the game, he was 1-1 with a 7.97 ERA in four starts this month.

He gave up two runs on five hits over six innings Friday, while striking out seven and walking two. Gray left the game with Oakland leading 4-2.

"He had a little bit of a (left) hip thing that was bothering him, so I didn't want to mess with that," A's manager Bob Melvin said of Gray. "He's had a lot of innings this year. He felt it once or twice in the game, and after that inning he felt it again."

Gray said his hip hurt in previous start, too, and there's a chance Gray could miss his final start of the season Wednesday against the Los Angeles Angels in Anaheim.

"I'm not sure," Gray said. "It's going to be sore tomorrow. That's how it was last time."

Left-hander Sean Doolittle blanked the Giants over the final 1 1/3 innings, escaping a bases-loaded jam in the eighth then pitching a perfect ninth for his second save of the season.

Giants right-hander Mike Leake (10-10) gave up four runs on six hits, including two homers, over six innings. He struck out three and walked two. Leake is 1-5 in eight starts since coming to the Giants from Cincinnati in a trade on July 30.

"Obviously it's not exactly what I had in mind," Leake said. "It's baseball. I'm not going to get down on it too much."

Third baseman Matt Duffy hit a two-run homer for San Francisco, and center fielder Jarrett Parker had a monstrous solo home run into the second deck in right field in the seventh. Rookie right fielder Mac Williamson had his first two major league hits in his first big-league start.

Burns went 2-for-4 with a double. A's left fielder Sam Fuld had two hits in three at-bats and scored twice. Second baseman Eric Sogard went 2-for-4 with a triple.

Burns gave the A's a 3-2 lead with his two-run blast in the third inning off Leake. Butler made it 4-2 with an opposite field solo home run to right in the sixth, his 14th shot of the season.

The Giants cut Oakland's lead to 4-3 in the top of the seventh on Parker's leadoff home run against A's rookie reliever Ryan Dull, who had opened his career with 11 scoreless innings over eight relief appearances. Dull pitched 1 2/3 innings, allowing two runs on three hits.

"He's got incredible power," said Williamson, who played much of this season with Parker at Triple-A Sacramento.

The A's responded with a run in the bottom of the seventh, making it 5-3. Fuld grounded a leadoff single to right off reliever Jeremy Affeldt then tagged up and went to second on Burns' flyout to deep center. Right fielder Josh Reddick lined a two-out single to center, driving in Fuld.

San Francisco scored a run in the eighth, cutting Oakland's lead to 5-4. With runners on first and second and two outs, designated hitter Marlon Byrd brought Duffy home with a single off Doolittle. Doolittle walked Parker, loading the bases, but he retired Williamson on a pop up to catcher Stephen Vogt in foul territory.

"He threw some good pitches inside," said Williamson. "I just couldn't quite get on top of it. I felt like I was seeing it pretty good all night. He's their go-to guy."

Duffy gave the Giants a quick 2-0 lead in the top of the first, crushing Gray's 1-0 pitch over the left-center-field fence with one out and second baseman Kelby Tomlinson on first.

Oakland answered with a run in the second inning. Third baseman Danny Valencia grounded a leadoff double down the right-field line, then tagged up and moved to third on Vogt's fly out to deep right. After Leake walked Butler, Sogard grounded into a force play, driving in Valencia.

NOTES: A's LHP Barry Zito and Giants RHP Tim Hudson, who are former Oakland teammates, will face each other Saturday. They held a joint press conference before Friday night's game. Hudson will retire after this season, and Zito, who played seven seasons for the Giants, likely will, too, although he hasn't made a final decision. "I don't think we could have written a better script," Hudson said. "We had some of our best years here in Oakland." Said Zito: "I'm so grateful I get to end everything on a Bay Area note." ... Oakland C Stephen Vogt started his first game at catcher since Sept. 6 when he sustained a painful groin injury.