Davis also was hit by a pitch to reach base in all of his five plate appearances in the opener of a four-game series.

Reliever Yusmeiro Petit (1-0), Oakland's third pitcher in the game, held Toronto to one hit and one walk and had one strikeout in 2 2/3 innings to earn the win.

Oakland starter Andrew Triggs left the game in the third inning due to right forearm nerve discomfort. He allowed one run, one hit and two walks with a strikeout in 2 1/3 innings. He was replaced by Santiago Casilla, who allowed three runs, three hits and two walks in two innings.

Triggs, who said he experienced numbness in his right thumb and index and middle fingers much of the outing, is being sent back to the Bay Area to be examined.

Toronto starter Aaron Sanchez (2-4) allowed four runs, five hits and four walks while striking out eight in four-plus innings.

The Blue Jays led 1-0 in the second after Kevin Pillar doubled, took third on Russell Martin's flyout and scored on a fielder's choice grounder to second by Kendrys Morales.

Oakland scored three in the third. Matt Joyce singled and scored on Jed Lowrie's double, and Davis hit his 13th homer of the season.

The A's added four in the fifth. Sanchez was lifted after walking Lowrie to lead off the inning. Seung Hwan Oh replaced him and allowed a single to Davis and the seventh homer of the season to Olson. Chapman doubled and scored on Dustin Fowler's single.

Toronto scored three in the bottom of the fifth. Richard Urena singled, Curtis Granderson walked, and Justin Smoak hit an RBI double. Petit replaced Casilla and allowed Yangervis Solarte's RBI single and Pillar's sacrifice fly.

Toronto reliever John Axford hit Davis with a pitch and gave up Chapman's eighth homer of the season in the sixth, and Oakland led 9-4.

Oakland's Ryan Dull walked Martin and allowed a single to Dwight Smith Jr. in the eighth before Lou Trivino replaced him with two outs. Urena singled to load the bases, and Granderson walked to force in a run.

Oakland scored an unearned run in the ninth against Jake Petricka on a single by Marcus Semien, a passed ball and an RBI single by Lowrie.

--Field Level Media