SAN FRANCISCO — A.J. Griffin knows plenty about Barry Zito's pitching pedigree, like that AL Cy Young Award the left-hander won while with Oakland in 2002.
Zito hung in there against his former club to outdo Griffin, and the Athletics missed on a chance to sweep the reigning World Series champions in a 5-2 loss Thursday that snapped their six-game winning streak.
While right-handed, Griffin is even considered a younger version of the veteran southpaw with his similar style and big curveball. Griffin gave up four runs and five hits, struck out five and walked one in 5 2-3 innings.
"Barry has been around a long time for a reason. He did a great job of keeping his team in the game. Despite the walks, he got us," Griffin said. "My job is to not let them score and they scored four runs off me. It was pretty disappointing."
The A's had chances against Zito in each of the first five innings but managed only Coco Crisp's RBI single in the second. Crisp had the only three Oakland hits off the lefty, too.
"You saw the ball to strike ratio with Zito and it wasn't good," A's manager Bob Melvin said. "He ended up making big pitches when he had to, whether he was behind in the count or not."
Pablo Sandoval hit a go-ahead two-run single in the sixth and Brandon Belt doubled in two runs in the four-run inning to help Zito end a six-start winless stretch.
A day after San Francisco made three errors and two other defensive miscues, the Giants finally got to Griffin (5-4) for their lone win in the four-game interleague rivalry between last year's West division champions.
"There's some pride involved," Giants manager Bruce Bochy said. "The last thing you want to do is get swept here in this Bay Series."
Zito (4-3) won against his former club for his first victory since beating San Diego at home April 21. The Giants improved to 7-0 in his home outings and have won 13 straight regular-season games started by Zito at AT&T Park.
San Francisco hasn't lost a home start by Zito since last Aug. 2 against the New York Mets.
Yoenis Cespedes added an RBI single in the seventh for the A's, extending his career-best hitting streak to 12 games.
Oakland (31-24) missed a chance to move a season-best nine games over .500 and lost for only the second time in 13 games. The A's have dropped 11 of their past 14 in the Giants' waterfront ballpark, which drew a sellout crowd of 41,250 for the afternoon finale.
"I think our team showed a lot of fire and we were competitive," A's third baseman Josh Donaldson said. "You go through a season and get tons of opportunities when you don't come through. But at the same time we're playing the game right way and I guarantee you we'll be ready for the White Sox."
The Giants lost the first three games of this Bay Area rivalry to drop the season series for the first time since going 2-4 in 2008 after a sloppy 9-6 loss Wednesday night.
San Francisco avoided its first season sweep by the A's since the clubs began playing interleague matchups in 1997.
"Last night we were pretty tenacious," Melvin said. "They roared back and we not only stemmed the tide but even added on. We feel like every time we take the field we have a chance to win."
Zito faced trouble in each of his first five innings before finishing his day with a 1-2-3 sixth. He delivered just the third quality start in the past 16 by the Giants' struggling rotation. Zito is 3-4 in seven career starts against his old team.
"I get some juice just because it's a tough team," Zito said. "We've got a lot of talent in the Bay right now. It's good to see. We definitely know what we need to do, we have to go out there and be better on the starting side."