OAKLAND – Yoenis Cespedes uncoiled a powerful swing and then froze, one step into his home run trot, still partly in the batter's box, watching his towering eighth-inning drive arc over the left-field fence.

After a 5-2 win over the Seattle Mariners on Sunday, that image seemed to symbolize the A's – on the cusp of the playoffs for the first time in six years, with one foot in.

With three games to play, the A's hold a three-game lead over the Los Angeles Angels and the Tampa Bay Rays for the second American League wild card. Oakland can secure that berth with one more victory or a loss by both the Angels and Rays.

In addition, the A's trail division-leading Texas by two games, meaning they still could surpass the Rangers in the American League West. Texas arrives at the Coliseum tonight for each team's final series.

"We're just going to try to win (tonight)," A's manager Bob Melvin said after his team won behind a strong bullpen effort and more timely slugging. "I think we're best suited to just do that and not worry about all the different variables."

After the A's completed a sweep of the Mariners for their fifth win in six games, though, outfielder Jonny Gomes said: "We've put ourselves in a position to where we don't have to scoreboard-watch. We just control our own destiny, and that's what we wanted to do."

That the division is still up for grabs entering the final series of the regular season is perhaps the unlikeliest aspect of the A's improbable run.

Since falling to 22-30 after a season-high nine-game losing streak June 1, the A's have the best record in the majors at 69-38 (.645).

"We've got our eyes set on (winning the West)," said Grant Balfour, who earned his 22nd save Sunday. "The whole year, that's what we wanted to try and do, and it was a matter of whether it was feasible at this time.

"And if it is, obviously we want to win it. There's no doubt about that."

Cespedes broke a 2-2 tie that had lasted since the third inning with his 23rd homer. He later explained that he watched its path thinking it might curve foul.

Two batters later, Josh Reddick hit a two-run moon shot into the second deck in right field for his 32nd homer.

Cespedes also got the A's on the board in the first inning, driving in Stephen Drew with a triple, and then tagged up and scored on a shallow fly ball to center field. He slid home safely as Franklin Gutierrez's throw bounced off the pitcher's mound, a day after Cespedes scored from first base on a single.

The A's are 79-46 when Cespedes starts and 12-22 when he doesn't. Melvin cited that disparity after the game, saying, "I don't know of anybody that has a bigger impact on a team than Yoenis has for us."

Reddick threw out Justin Smoak at home in the second inning for his 15th outfield assist – the most by an A's outfielder since Mike Davis had 16 in 1983 and a boost for Tommy Milone as the left-hander navigated a rocky start.

Eight of Seattle's first 14 batters hit safely, but only two scored.

After Milone departed in the fifth, five Oakland relievers combined for 4 1/3 scoreless innings.

Jerry Blevins got out of a first-and-third situation with two outs in the fifth by getting Smoak to ground out. In the seventh, Ryan Cook put runners on first and third with nobody out, then finished the tightrope act by striking out the side.

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