Cespedes supplied a two-run triple during a four-run first inning that staked the A's to an early lead and added a solo shot in the eighth, capping the scoring.
Josh Reddick also knocked in a trio of runs while Seth Smith went 2-for-3 with a run-scoring double for American League West-leading Oakland, which won a seventh in nine games overall.
A.J. Griffin (10-7) notched the win despite surrendering four runs on four hits over seven innings. He walked two and struck out five.
Blue Jays starter Esmil Rogers (3-5) was lit up for eight runs (six earned) on nine hits in a 4 1/3-inning effort.
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