OAKLAND, Calif. -- Toronto manager John Farrell, who celebrated his 50th birthday, said luck had nothing to do with it.
"We earned that one," he said. "It's been a while since we shook hands after a game. Oddly enough, we had to play another extra-inning game to do it."
The Blue Jays ended a six-game losing streak a day after they fell to the A's 5-4 in 15 innings.
"We took some calculated chances and gambled on a few pitches," Farrell said. "That last inning we rolled the dice, trying to make something happen."
Cooper hit a solo homer off Ryan Cook with one out in the ninth. Cook gave up a tying, three-run shot in the ninth on Friday night.
"I guess you can't walk every game off," said A's third baseman Brandon Inge, who had a 13-game hitting streak end.
The A's had won three in a row. They loaded the bases in the 10th, but Josh Reddick was called out on strikes.
Oakland went into extra innings for the sixth time in its last 24 games, a span that includes a pair of 15-inning wins.
"You're not going to win all those games, yet you expect to," A's manager Bob Melvin said. "We didn't come through this time."
A's rookie right-hander A.J. Griffin left with two outs in the second with tightness in his pitching shoulder.
Griffin, who lowered his ERA to 2.42, allowed a leadoff single to Yunel Escobar and then retired five straight before being replaced by Jordan Norberto, who gave up four hits over a career-high 3 2/3 innings.
Blue Jays starter Ricky Romero gave up a run and three hits in seven innings. He remained winless over his last eight starts, in which he received a total of six runs of support.
"It comes down to trusting my fastball," Romero said. "Everything else works on that. When I am able to control my fastball, the game comes to me instead of me falling behind."
Sierra was thrown out at the plate trying to score on Anthony Gose's two-out double in the second.
The Blue Jays also had two runners in scoring position in the fourth before Norberto got Yan Gomes on a short flyout and Sierra on a grounder.
Davis extended his hitting streak to a season-high nine games. ... Toronto RHP Brandon Morrow threw 43 pitches Friday in his second rehabilitation start for Class A Dunedin. ... LHP Aaron Laffey (2-2, 4.20) goes for the Blue Jays in Sunday's series finale against LHP Tommy Milone (9-8, 3.68). ... The A's became the first AL team to win a pair of 15-inning games on the same homestand.