Down 3-1 going into the last inning, the Giants ripped together four hits and four runs in the top of the ninth to earn the 5-4 victory.
Ryan Cook (2-2) had been nearly unhittable before earning the loss, as he came into the game with a 0.57 ERA in 31 2/3 innings. Friday night proved he's not invincible after all after he allowed two hits, two walks, and four earned runs without recording a single out in the ninth inning. It was his first blown save since taking over the closer's role full time earlier this month.
Brandon Belt's two-run double off Cook tied the game, and Hector Sanchez and Gregor Blanco followed that up with a pair of RBI singles.
Blanco finished with two hits, two RBI, and three steals.
Tim Lincecum's quality start was a good sign for Giants fans. He allowed three earned runs and three hits in six innings of work while striking out eight, but he still showed control issues by walking four. His ERA on the season is a disastrous 6.07.
Clay Hensley (3-3) pitched just one-third of an inning in the bottom of the eighth but it was enough for him to earn the win. Santiago Casilla gave up a solo homer to Josh Reddick in the bottom of the ninth, but still earned his 20th save.
Reddick went 2-for-3 on the evening, and the homer was his team-leading 16th of the season.
The Giants will send one of the games top young left-handers to the hill tonight in Madison Bumgarner, who has been terrific this season with an 8-4 record, a 2.92 ERA, and 78 strikeouts to just 19 walks.
He's also been a model of consistency. Since lasting just four innings in his season debut on April 7, Bumgarner has strung together 13 consecutive starts pitching at least six innings.
The 23-year old's last start was of one of his best, lasting eight innings against Seattle while allowing just three hits and one earned run on Sunday, though he earned the no decision, as the Giants fell to the Mariners 2-1.
Bumgarner is 3-0 in four June starts with a 2.43 ERA.
The Athletics will answer with Tyson Ross, who is replacing the injured Bartolo Colon in the rotation.
Ross has been ineffective as a starter thus far, going 2-6 with a 6.11 ERA. He lost six of seven starts between April 28 and May 30 before being demoted to Triple-A Sacramento.
The right-hander returned to the big leagues on June 16, allowing just one hit and two earned runs in six innings of work in a no decision against San Diego, but he also issued four walks.
"His ball-to-strike ratio was not great but he did use his breaking ball effectively," A's manager Bob Melvin said of Ross's last outing. "He certainly kept the damage down. You could say he was effectively wild."
Ross was a hard-luck loser in a start against the Giants on May 19, going six innings while allowing two earned runs.