Buster Posey again provided a key hit, this time a two-run double in the first inning off A's right-hander Kendall Graveman. It followed Denard Span's single and Joe Panik's walk. Gregor Blanco added an RBI single off Sean Doolittle in the seventh.
As was the case Thursday, when left fielder Angel Pagan hustled in to make a running catch, center fielder Span sped forward to rob Danny Valencia of a bloop hit.
The A's didn't advance a runner to second base until Mark Canha doubled with one out in the sixth. Chris Heston, who followed Peavy to the mound, then induced Josh Reddick's groundout and Valencia's flyout.
Graveman, making his fifth start in six exhibition appearances, surrendered two runs and four hits in five innings.
"I got better every start. Now I can turn it up for the regular season," said Graveman, Oakland's projected No. 4 starter.
A's Up Next: Manager Bob Melvin is expected to make the team's final roster cuts Saturday as the Bay Bridge Series moves to Oakland for its conclusion with a 1:05 p.m. PT confrontation, live on MLB.TV's free preview. Left-hander Felix Doubront will start for the A's.
Giants Up Next:Matt Cain will attempt to cement his status as the Giants' No. 5 starter when he confronts Oakland in the finale of the three-game exhibition series. It should be a placid day for the Giants, whose 25-man Opening Day roster is essentially set.