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Still, Greinke said after the outing he didn't feel quite as good as last season with the Dodgers, when he went 19-3 with a 1.66 ERA.
"No, I wasn't as good as that," said Greinke, despite throwing only nine balls. "I still have a ways to go before I make quality pitches like that regularly."
The A's scored twice in the third inning against Arizona right-handed reliever Tyler Wagner. Eric Sogard doubled, and Billy Burns tripled to account for the runs.
The D-backs opened the scoring when second baseman Jean Segura led with a homer of A's starter Felix Doubront. Rookie right-fielder Gabby Guerrero knocked in four runs with a first-inning single off Doubront and a third-inning three-run homer off reliever Chris Smith. Doubront gave up two runs on five hits with a walk and a strikeout in his two innings.
The D-backs signed Greinke as a free agent in December to the richest contract in franchise history -- six years at $205 million -- and he is expected to stabilize their starting rotation.
"He's next level," second-year manager Chip Hale said before the game. "He's been there so many times. We're just looking for him to get through the outing healthy and do what he has to do to get his work done. We're not worried about results. We're just worried about him being ready for April."
Up next for the D-backs: The D-backs play the Dodgers on Saturday at Camelback Ranch at 1:05 PM MT and will get their first look at Shelby Miller, the right-hander who came to Arizona last December in a deal with the Braves. The D-backs went into camp trying to sort out the back end of their rotation, but they consider the first two spots solid with Greinke and Miller. Fans catch watch the matchup live on MLB.TV.
Up next for the A's: Left-hander Rich Hill, signed by the A's to a one-year, $6 million deal this winter, will be making his Cactus League debut Saturday in a home start against the Brewers at Hohokam Stadium, with first pitch scheduled for 12:05 p.m. PT. Another offseason acquisition, hard-throwing righty Liam Hendriks, is also scheduled to pitch in the game. Fans can listen live on Gameday Audio.
Barry M. Bloom is a national reporter for MLB.com and writes an MLBlog, Boomskie on Baseball. Follow @boomskie on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.