Matt Olson hit a grand slam, and Khris Davis belted his major-league-leading 47th home run of the season as the Oakland Athletics routed the host Seattle Mariners 9-3 Wednesday night.

The A's (96-63), who have already clinched a playoff berth, closed within 1 1/2 games of the New York Yankees in the race for the American League's top wild-card seed and the chance to host next week's one-game playoff.

Mariners right-hander Felix Hernandez (8-14) lasted just four-plus innings in losing his eighth straight decision. He gave up five runs (four earned) on three hits, with two walks and four strikeouts.

Hernandez allowed solo homers in each of the first two innings, to Marcus Semien and Chad Pinder, respectively. It was Semien's 15th home run and Pinder's 13th.

The Mariners (86-72) tied it on Ben Gamel's two-run double with the bases loaded in the second.

It remained tied at 2-2 until the fifth, when the A's batted around in scoring six times.

Oakland's Mark Canha led off the inning by getting hit by a pitch. Josh Phegley then hit a ball back to the mound that Hernandez threw away while trying to get a forceout at second, putting runners at first and third. Nick Martini grounded a single to right field to score Canha with the tiebreaking run and end Hernandez's night.

Semien greeted right-hander Chasen Bradford with a run-scoring single to left. After a groundout, the Mariners intentionally walked Davis to load the bases. The move backfired when Olson hit a 1-1 pitch just over the wall in right-center field, his 29th homer, to give the A's an 8-2 lead.

Despite being staked to a six-run lead, Oakland right-hander Edwin Jackson couldn't make it through the fifth inning to qualify for the victory.

Jean Segura led off the bottom of the fifth with a walk, advanced to third on a single by Robinson Cano and scored on a sacrifice fly by Nelson Cruz. After Denard Span grounded a single to right, Jackson was replaced by left-hander Ryan Buchter (6-0), who got the win.

A passed ball allowed the runners to advance to second and third, but Buchter caught both Kyle Seager and Dan Vogelbach looking at called third strikes to end the inning.

Jackson pitched 4 1/3 innings and allowed three runs on five hits. He walked five and struck out two.

Davis closed the scoring with a solo shot off Seattle right-hander Casey Lawrence in the seventh inning.

--Field Level Media