Gallagher walked six in four hitless innings, Ryan Sweeney and Jack Cust hit back-to-back homers in the first and the Oakland Athletics beat the Detroit Tigers 5-2 on Wednesday.

Gallagher, who had been out since Aug. 20 with shoulder fatigue, struck out six and threw 44 of his 88 pitches for strikes.

"It was a little different out there with all those walks and strikeouts and no hits," he said. "I felt good and my arm didn't bother me at all. I missed the plate on a few pitches, but I was able to come back and make quality pitches to get outs."

Gallagher walked the bases loaded in the first and fourth, but got out of both jams. The rookie right-hander struck out Jeff Larish to end the first and got Brandon Inge to fly out to end the fourth.

"He pitched pretty well, but he had to battle his command as you can see from the strange strikeout and walk totals," Oakland manager Bob Geren said. "He was able to make his pitches when he needed them - he's going to be one of the good young pitchers in this league."

Fellow rookie starter Armando Galarraga (12-6) didn't fare quite as well for Detroit. He allowed five runs and eight hits in four innings, extending his winless stretch to four starts.

"He looks like he's starting to burn out a little bit," Tigers manager Jim Leyland said. "We'll see how it plays out - he's going to get an extra day before his next start, but he might be running on empty."

Galarraga retired the first two batters before Sweeney and Cust went deep to start the A's toward their fourth win in five games.

"It's always good to get ahead early, and when you get homers, it feels even better," Sweeney said. "Gallagher gave us four good innings, we added some more runs and the bullpen kept us ahead. That's a positive win."

Oakland scored three runs in the fourth to take a 5-0 lead. Eric Patterson had an RBI single and Aaron Cunningham drove in a pair with a two-out base hit.

Huston Street (6-5) worked a scoreless seventh to get the win and Brad Ziegler pitched the ninth for his eighth save in eight tries.

"Getting the two homers in the first in a big ballpark was huge for us," said Geren, who used six relievers. "We got some key hits when we needed them and then the pen held them down."

Miguel Cabrera led off the sixth with a single for Detroit's first hit and scored on Ryan Raburn's two-out, two-run single. Alan Embree entered with two runners on and got Curtis Granderson to fly out to end the inning.

The Tigers got a runner on in the ninth against Ziegler, but Granderson was easily doubled off first to end the game after Magglio Ordonez's flyout to deep center.

"I thought the ball was way over the center fielder's head, but it is still a dumb mistake on my part," Granderson said. "My run didn't even mean anything, since we were down three, so I had no business doing that."

Notes: Granderson was the second Tigers player to be doubled off during the game. Oakland 3B Jeff Baisley made a diving stop of Marcus Thames' liner with the bases loaded in the sixth, then threw to first in time to retire Mike Hessman. ... The teams combined to use 12 pitchers, who struck out 22 and walked 11.