Yoenis Cespedes hit a tiebreaking home run in the eighth before Josh Reddick added a two-run shot later in the inning, lifting the Oakland Athletics to a 5-2 win and a three-game sweep of the Seattle Mariners.
Cespedes added an RBI triple for the Athletics, who are two games behind the AL West-leading Texas Rangers. The teams close out the season with a three- game set against each other in Oakland.
"This last series is going to be pretty big for us. That was our goal ever since the start of the season," Athletics starting pitcher Tommy Milone said. "Obviously you want to win the division, you don't want to hope for the wild card spot."
Oakland is three games ahead of Los Angeles for the second wild card spot.
Cespedes' solo blast to left field was surrendered by Shawn Kelley (2-4) with one out in the eighth. Lucas Luetge took over on the mound for Seattle and failed to retire either of the two batters he faced.
"The A's are feeling it right now. Just huge home runs for them late in the ballgames the last couple nights," Mariners manager Eric Wedge said.
Brandon Moss singled and swiped second base before Reddick launched his 32nd homer of the season to right field.
The late power surge made a winner out of Sean Doolittle (2-1), while Grant Balfour pitched the ninth for his 22nd save.
Milone allowed two runs on nine hits in 4 2/3 innings for Oakland. His counterpart from Seattle, Erasmo Ramirez, scattered three hits, walked four and struck out six over 6 1/3 innings.
The A's scored two first-inning runs with only one hit. Stephen Drew worked a one-out walk and scored on a triple by Cespedes. Moss followed with a sacrifice fly to center field.
Seattle tied the game in the third. The Mariners opened the frame with three consecutive hits, as Franklin Gutierrez scored on a Kyle Seager single. Casper Wells, who followed Gutierrez's leadoff double with a base hit, eventually was driven home by Justin Smoak's two-out single.
The Mariners had homered in 18 straight games, one shy of the franchise record set in 1999 ... Seattle was 5-for-15 with runners in scoring position.