Brandon Inge had three RBIs, including a two-run double to cap a three-run ninth as the visiting A’s sent reeling Colorado to its seventh consecutive defeat.
Seth Smith and Brandon Moss belted two-run homers and Jonny Gomes had a solo shot for the A’s, which rallied from deficits of 6-2 and 8-5.
Todd Helton belted a grand slam and Michael Cuddyer had four hits with a pair of homers for the Rockies, who tumbled to 0-8 in interleague play.
Jerry Blevins (1-0) worked two scoreless innings for his first win since April 2010 and Ryan Cook worked around a leadoff single in the bottom of the ninth for his second save.
Rockies closer Rafael Betancourt (1-2) suffered his second blown save, giving up Collin Cowgill’s tying sacrifice fly before Inge’s double.
Helton’s blast in the bottom of the first erased a 2-0 deficit and set the franchise record with seven grand slams, eclipsing the mark held by Dante Bichette and Andres Galarraga.
Oakland got within 6-5 in the fourth on Moss’ homer — his third in two games — but Cuddyer’s second blast in the bottom of the inning built the lead back to 8-5 before the A’s clawed back with single runs in the sixth and seventh and three in the ninth.