OAKLAND, Calif. -- Yoenis Cespedes hit a go-ahead homer in the eighth inning to move Oakland a win closer to the club's first playoff berth in six years, and the Athletics beat the Seattle Mariners 5-2 on Sunday to stay right on the heels of Texas in the AL West race.
Cespedes also hit an RBI triple and Brandon Moss had a sacrifice fly in the first inning for the A's, who pulled within 1 1/2 games of Texas. The Rangers were playing Game 2 of a doubleheader at home Sunday night against the Angels.
The two-time reigning AL champion Rangers come to the Coliseum for the final three games starting Monday with the division crown still up for grabs.
Oakland (91-68) leads Los Angeles by 2 1/2 games for the second AL wild card.
Cespedes sent a 1-2 pitch from Shawn Kelley (2-4) towering into the left-field seats for his 23rd homer. He keyed another dramatic victory for the A's a day after Moss hit a three-run drive in the 10th inning of Oakland's 14th walkoff win.
Josh Reddick connected with a two-run shot for his team-leading 32nd homer two batters later as the A's made it a sweep.
Surprising Oakland, with its energetic roster of rookies, has hit 20 home runs in its last nine games and has a majors-best 110 since the All-Star break.
But the A's will have to wait at least one more day to secure a playoff berth. The Angels kept their hopes alive by rallying in the ninth to win the opener of the doubleheader at Texas.
Oakland dropped its magic number to two for clinching the club's first playoff berth since 2006. The A's were swept that year by the Tigers in four games of the AL championship series.
Sean Doolittle (2-1) pitched a perfect eighth for the win. Grant Balfour finished for his 22nd save.
Kyle Seager and Justin Smoak each hit RBI singles in the third as Seattle tied it. The Mariners were 0 for 17 with runners in scoring position this series before Carlos Triunfel's second-inning single. But Smoak was thrown out at home as the A's saved a run.
Milone gave way to Pat Neshek with two outs in the fifth and Casper Wells on third with a triple. But Neshek was done after walking Jesus Montero on four pitches.
Jerry Blevins relieved and retired Smoak on a grounder in which third baseman Josh Donaldson made a lunging, run-saving stop.
All-Star Ryan Cook allowed Trayvon Robinson's leadoff single in the seventh, then struck out the side.
Charlie Furbush relieved Seattle starter Erasmo Ramirez after a one-out single to Seth Smith in the seventh. After pinch-hitter Derek Norris struck out, Cliff Pennington walked and Jemile Weeks entered to pinch run for Smith at second.
But Coco Crisp hit a high fly ball to right on the first pitch to end the inning.
Then, Cespedes delivered.
A's starter Tommy Milone allowed a leadoff double to Franklin Gutierrez to start the game but got out of it unscathed. The left-hander, whose 13 wins are already an Oakland rookie record, allowed two runs and nine hits in 4 2-3 innings. He struck out three and didn't surrender a walk.
Gutierrez, the Seattle center fielder, left the game before the bottom of the third with tightness in his left groin after batting in the top half. Gutierrez, who missed Friday's series opener after crashing into the wall a day earlier at Anaheim, hit a pair of doubles and scored a run following an 0-for-5 day Saturday.
When Crisp drew a leadoff walk in the third, it ended a 16-inning streak without a free pass for Ramirez. The right-hander walked four to double his total in eight major league starts.
NOTES: Cespedes hit his fifth homer vs. the Mariners in the seventh inning or later. And Oakland won the season series 12-7. ... Mariners manager Eric Wedge rested 2B Dustin Ackley for most of the day and got a second straight look at Triunfel, who played SS on Saturday. ... RHP Jarrod Parker (12-8) pitches for the A's in Monday night's series opener against LHP Martin Perez (1-3) and the Rangers. A's manager Bob Melvin said struggling LHP Travis Blackley -- with two wins in his last seven starts -- is still down to start Tuesday night against Texas. "I don't know that we have any other options, to tell you the truth," Melvin said. ... LHP Brett Anderson, who is nursing a strained right oblique but could return to pitch a one-game wild card playoff, played light catch and is set to throw off a mound Monday.