Both homers came off Jeff Samardzija, who became the first Giants starter to last six innings in a Cactus League game. Samardzija surrendered six runs and six hits while striking out three.
"You look at it as a whole and that was exactly what we wanted out there," said Samardzija, who pitched for the Chicago White Sox last year and shared the American League lead in home runs allowed with 29.
• Samardzija has "great day" despite homers
A's starter Chris Bassitt, who allowed only two hits in five innings spanning his previous two starts, surrendered four runs and eight hits in 5 1/3 innings this time.
"I feel like I'm just tweaking stuff at this point, where in the past I was so worried about throwing strikes," Bassitt said. "I feel way ahead of where I used to be at this point, and I feel great going into the season."
Each team notched a second-inning run. Oakland opened the scoring as Khris Davis hit a ground-rule double and came around to score on Josh Phegley's groundout. The Giants pulled even on Ehire Adrianza's RBI single, which scored Miguel Olivo.
Oakland inched ahead in the third. Eric Sogard singled, moved to third on a pair of wild pitches and scored on Billy Burns' sacrifice fly. The Giants tied it again in the fourth on Hunter Pence's leadoff home run, his third long ball of the spring.
A's Up Next: Right-hander Kendall Graveman will be on the mound Tuesday for a 1:05 p.m. PT start against the host Angels at Tempe Diablo Stadium. Relievers Marc Rzepczynski and Ryan Dull are also scheduled to pitch in the game.
Giants Up Next: It'll be all hands on deck Tuesday for the Giants as they play a day-night, split-squad doubleheader. In the 1:05 p.m. PT contest at Glendale, right-hander Jake Peavy will confront one of his former teams, the Chicago White Sox, whose starter will be San Francisco nemesis Mat Latos. Left-hander Ty Blach, who already has been optioned to the Minors, will confront Arizona in a 7:05 p.m. PT affair.
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, follow him on Twitter at @sfgiantsbeat and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.