Trailing 6-4 to start the frame, the Blue Jays got a one-out single from Melky Cabrera to begin the comeback.
Octavio Dotel then entered and Arencibia greeted him by lacing a hit that rolled to the center field wall, driving in all three runners.
DeRosa also supplied three RBI for the Blue Jays, who overcame cold, wet conditions after the start of the contest had been delayed 2 1/2 hours by the foul weather.
Aaron Loup (1-0) earned the series-evening victory with a scoreless sixth and Casey Janssen secured the Toronto win with his second save.
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