BALTIMORE -- Jake Arrieta was done in by a two-out rally and a pair of Oakland home runs on Friday.
The Orioles starter fell behind in the count on seven of the first nine batters he faced, as Oakland took the first game of a three-game set, 5-2, before 18,297 at Camden Yards.
"Just one of those nights where nothing really felt right," Arrieta said. "Really wasn't able to establish my fastball early in the game."
Looking to rebound from a frustrating outing last weekend in Anaheim, Arrieta allowed a two-run homer to Eric Sogard in the second on Friday and a solo blast to Josh Reddick in the sixth.
Arrieta surrendered four runs on four hits and two walks. He struck out three on 105 pitches, but it was the two Oakland homers that helped the A's win their third straight game and seventh in the last 10.
The Orioles (12-8), who lost for the first time in five games, couldn't get much started against Oakland righty Brandon McCarthy, who scattered two runs on five hits and four walks in seven innings to pick up his first win.
"Strike one, that's the key around baseball, throwing strike one," center fielder Adam Jones said. "Successful pitchers do that and tonight he was throwing strike one and made us put the ball in play."
The Orioles took a 1-0 lead in the first first on a Nick Markakis sacrifice fly that scored Nolan Reimold, who doubled to lead off the game before taking third on J.J. Hardy's deep flyout to left.
Oakland (11-10) responded with a two-out rally in the second. Kurt Suzuki doubled into the left-field corner, scoring Kila Ka'aihue. Sogard then deposited an Arrieta offering into the right-field flag court in the next at-bat for a 3-1 Oakland lead.
The A's went deep again in the sixth, as Reddick launched a long blast into the Eutaw Street Reserve seats in center field. After getting Yoenis Cespedes to fly out to right, Arrieta's night was done.
"If I could have got my team through six with three runs, I would have been happy with that," Arrieta said. "I came up a hitter short. Just got to put this behind me. We're rolling now. We're 4-1 in our last five. I'm just going to try to get ready for New York on Wednesday and forget about this one."
The Orioles scored a run in the bottom of the sixth. After a Hardy double into right-center field, Jones went with a McCarthy offering, singling to right field to score Hardy easily, as Reddick bobbled the ball.
But after a walk to Matt Wieters, McCarthy got Chris Davis to ground out to first to escape the jam. McCarthy worked a quiet seventh to complete his outing.
"Anytime we can go out and get a few early, and hopefully the pitcher does his job, it kind of makes the game move faster and puts you in a positive mindset early," McCarthy said. "I wasn't really sharp, but I felt like I was able to make some pitches. There are a few hitters here and there I wish I could have back, but that's kind of like any game, I guess."
Oakland would tack on another run in the eighth, when Reddick singled home Coco Crisp with the A's fourth two-out run of the game.
"I thought the two tack-on runs were big," Orioles manager Buck Showalter said. "Solo home run, and the last one on the broken bat."
Sean Welsh is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.