Brandon Moss hit two home runs on Tuesday and the Athletics downed the Rockies, 8-5, in the opener of a three-game interleague series.
Colorado scored four in the first inning, but Oakland responded with a six-run third, highlighted by a two-run blast from Moss, who was called up from the minors on Wednesday.
He added a solo shot in the fifth while Brandon Inge went 2-for-3 with a homer and two RBI, helping the A's halt a three-game skid.
Bartolo Colon (6-6) got the win, surrendering five runs on nine hits over five innings. Ryan Cook allowed runners to reach first and second in the ninth before recording three straight outs to earn his first career save.
Tyler Colvin and Todd Helton both hit solo home runs for the Rockies, who lost their sixth straight game and fell to 0-7 in interleague play on the season.
"It's a script that we've been following quite a bit," said Rockies manager Jim Tracy. "We did a great job offensively in the first inning and we pitched a very poor third inning."
Jeremy Guthrie (3-5) was charged with seven runs on eight hits over five inning in the setback.
Oakland left the bases loaded in the top of the first and Colvin took advantage in the home half with a leadoff blast to center. Marco Scutaro followed with a triple and Michael Cuddyer plated him with a line drive base hit to center. Chris Nelson and Wil Nieves added consecutive RBI singles later in the frame, but the lead proved fleeting.
Guthrie hit Jemile Weeks to begin the third, then walked Josh Reddick with one down. Seth Smith and Inge followed with back-to-back doubles, pushing three runs across, and Moss' subsequent upper-decker to right-center put the A's on top. They weren't done, however, as Cliff Pennington added a two-out solo blast for a 6-4 advantage.
"I didn't think the team came into the dugout demoralized after giving up the (four) runs," said A's manager Bob Melvin. "Everybody knew you play the full nine innings."
Moss and Helton traded homers in the fifth and Inge capped the scoring with a blast to deep center in the seventh.
Moss was called up from Triple-A Sacramento on June 6. He has three home runs on the season...This is the first time the A's and Rockies are meeting since 2009, when Colorado swept a three-game series.