DETROIT -- The Oakland Athletics avoided a three-game sweep, yet still came out on the losing end.

Seth Smith homered, doubled and drove in four runs, and the Athletics beat the Detroit Tigers 12-4 in a matchup of AL playoff contenders. But the wild-card co-leaders also learned they would be minus starter Brett Anderson for the remainder of the regular season.

An MRI revealed Anderson sustained a Grade 2 strain of his right oblique muscle on Wednesday night, when the left-hander awkwardly fell off the mound and exited after two-plus innings.

Anderson was 4-2 with a 2.57 ERA after six games while coming off Tommy John surgery. The A's revealed the extent of his latest injury after their victory.

"He's a guy that's got ace-type of stuff. It hurts to lose a starting pitcher," Athletics manager Bob Melvin said. "But we've lost a lot of starters in the last month and a half, three."

Melvin said he doesn't know about Anderson's availability for the postseason.

The team also is without Brandon McCarthy, who was hit in the head by a line drive, and Bartolo Colon, who was suspended for using a performance-enhancing drug.

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Both clubs are in second place in their divisions, and Oakland is even with Baltimore for the wild-card spot.

The Tigers fell 2½ games behind the Central-leading Chicago White Sox, who played later at Kansas City.

Outscored 18-4 in the first two games, Oakland held down Miguel Cabrera to win the finale. Cabrera singled in four at-bats, and tops the AL in batting at .333.

Josh Donaldson hit a go-ahead single in a four-run sixth inning that made it 6-3, then had an RBI double to cap a six-run ninth that included Smith's three-run double.

"We're not the type of team to score a run here, a run there, two runs here. We're more of a big-inning team, more often than not," Smith said.

Pat Neshek (2-1) retired the only batter he faced and got the win.

Anibal Sanchez (3-6), who held Cleveland hitless for 6 2/3 innings in his last start, gave up six runs on six hits and two walks in 5 2/3 innings.

Smith hit his 14th homer, a solo shot in the fifth that made it 2-all. The Tigers retook the lead in the bottom half when Cabrera singled and scored on Prince Fielder's double.

The A's went ahead for good in the sixth. Brandon Moss hit a tying double with one out and after Chris Carter struck out and Smith was walked intentionally, Donaldson singled.

Phil Coke relieved and George Kottaras hit a liner that center fielder Austin Jackson misjudged, the ball sailing over his head for a two-run triple.

"It kind of knuckled. I was right there. It just took a left turn on me," Jackson said.

Kottaras felt fortunate.

"I knew I hit it good. I saw him coming in. I thought, 'Oh no, he's going to catch it,'" Kottaras said. "Then when I saw it go over his glove. I was like `Great!' But then I thought, `I've got to keep running."'

Andy Dirks led off the Detroit sixth with a home run off Jerry Blevins.

Yoenis Cespedes hit a bases-loaded sacrifice fly to start Oakland's scoring in the ninth.

The Tigers threatened in the first against Tommy Milone, loading the bases before Delmon Young grounded into an inning-ending double play.

"We missed a couple opportunities," Tigers manager Jim Leyland said. "Delmon hit a ball right on the button in the first inning, double-play ball, he hit it right on the nose. We had a couple other opportunities. We had some chances."

Detroit broke through in the second to take a 2-0 lead on Gerald Laird's RBI single and Jackson's sacrifice fly.

Second baseman Omar Infante's throwing error on an attempted double play gave the A's a run in the third. It was his 10th error in 51 games since being acquired from Miami, along with Sanchez, on July 24.

Notes

• Detroit C Alex Avila is no longer having headaches, according to Leyland. Avila sprained his jaw when he collided with Fielder chasing a foul ball on Sunday.
• Cespedes was the designated hitter because of a bone bruise on the bottom of the outfielder's foot that has lingered for the last few days.
• Oakland OF Coco Crisp missed his second game because of an eye allergy.
• The Athletics travel to New York for a three-game weekend series. Jarrod Parker faces CC Sabathia on Friday night.
• Rick Porcello and the Tigers host Sam Dedundo and Minnesota on Friday night.