"Dallas Braden set the tone. We all try to follow in those footsteps," Gonzalez said of his teammate's perfect game May 9. "I felt great just going out there pounding the strike zone."
An error by first baseman Aubrey Huff set up Coco Crisp's sacrifice fly in the third inning. The Giants managed only three hits and matched a season high with their fourth straight loss.
Gonzalez (5-3) allowed two hits in eight innings. He gave up a single to Freddy Sanchez in the first, then a one-out walk to Huff followed by a single to Andres Torres in the second. After that, he went 1-2-3 the rest of the way.
The left-hander struck out five and walked one in a 95-pitch gem. Closer Andrew Bailey, the reigning AL Rookie of the Year, finished the three-hitter for his seventh save in nine chances.
But not without a bit of drama. Bailey allowed Edgar Renteria's one-out single and walked Pablo Sandoval in a 10-pitch at-bat with two outs after starting 0-2 against him. Bengie Molina struck out to end it.
"No other way to sum it up than just plain fun," Bailey said. "To get Gio the win there was great. That was a fun at-bat. I don't think I've had one of those in a while."
Manager Bob Geren said he didn't want Gonzalez to have to face San Francisco's lineup a fourth time as he neared the 100-pitch mark. It was already a career-best for Gonzalez going eight innings.
"The entire performance was impressive," Geren said.
Cain (2-4) pitched a five-hitter for his first complete game since last Aug. 3 against Houston. He was hurt again by a lack of run support, his third straight outing with the Giants held to two or fewer runs.
"I thought we gave away some at-bats today to be honest," manager Bruce Bochy said. "They're pressing, there's no getting around it."
Crisp had another productive day in his second game of the season. The new Oakland center fielder made his A's debut Friday night with two RBIs in a 6-1 win over the Giants after coming off the disabled list from a broken left pinkie finger.
The Athletics scored when Adam Rosales was hit by a pitch and Cliff Pennington reached on Huff's error. Rajai Davis sacrificed and hit Crisp hit a fly ball.
Cain lost his third straight start. He was coming off consecutive losses to San Diego in which he struggled with his control and walked 11 total batters in those two outings. He issued only one free pass Saturday and struck out four.
"It was definitely a tough loss," he said. "It just came down to one situation and it worked out in their favor."
Bochy was planning to shake up his lineup Sunday, then the Giants will have a much-needed day off Monday following 13 straight.
Cain fell to 2-5 with a 2.44 ERA in seven career outings against Oakland.
"He pitched his heart out," Bochy said. "Got the leadoff hitter on six times and he had to pitch out of it, and he did it. He really did a great job today. That's why this is another tough one. We've had some gut-wrenching losses."
The Giants were 0 for 9 with runners in scoring position on Friday night, and again couldn't get anything going against Gonzalez.