"My command was really good today," Garrett said. "In the bullpen, I was working on keeping everything down just to prepare for today. I was able to pound the zone and not miss by much where I wanted to go. My breaking ball and changeup were working really well. I was able to keep the hitters off balance."
The Reds have three open rotation spots and Garrett has a 0.79 ERA through four games -- although he allowed five unearned runs in a lackluster previous outing. Since Anthony DeSclafani went down Sunday with an elbow injury -- and was scratched for Monday -- Cincinnati has gotten multiple nice performances from their pitching prospects.
"It's unfortunate for a teammate to hear bad news," Garrett said. "I think we're all trying to step up and fill the role as much as we can. I think it will be a domino effect from here on out."
A's starter Kendall Graveman pitched 3 2/3 innings with three earned runs, four hits, one walk and one strikeout.
"I didn't locate as well as the game went on," Graveman said. "I would like to have a few quicker innings, but sometimes that's how it goes."
Jesse Hahn was impressive in four innings of relief for the A's.The right-hander held the Reds hitless while striking out two batters. He has a 3.12 ERA this spring.
The Reds took a 1-0 lead in the second inning. Jesse Winker reached on a single and later scored on Brandon Dixon's sacrifice fly. Dixon earned a three-RBI day when his two-run home run to left-center field in the fourth made it a three-run game.
The A's posted just three hits and didn't get on the scoreboard until Chris Parmelee homered to left field with two outs in the ninth.
"We didn't swing the bat real well today," A's manager Bob Melvin said. "You'll have days like that."
Athletics Up Next: Sean Manaea will make his fourth appearance this spring when the A's host the Rockies at 1:05 PT Tuesday at Hohokam Stadium. Manaea has a 6.14 ERA this spring. Reliever Sean Doolittle also is expected to make his first Cactus League appearance this spring.
Reds Up Next: Two pitchers competing for rotation spots will be on the mound Tuesday vs. the Dodgers at 4:05 p.m. ET in Glendale. Tim Adleman, who was roughed up his last time and sustained a right shoulder contusion from a line drive, will get the start. Prospect Robert Stephenson is due to enter from the bullpen.
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Mark Sheldon has covered the Reds for MLB.com since 2006, and previously covered the Twins from 2001-05. Follow him on Twitter @m_sheldon and Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.