Athletics 4, Mariners 0: Sam Fuld and Brandon Moss homered while Jon Lester struck out seven in six innings as visiting Oakland won its second straight over Seattle.

Lester (15-10) improved to 5-3 with a 2.30 ERA since joining the Athletics after allowing four hits and four walks to help Oakland move 2 1/2 games clear atop the American League wild-card race. Fuld and Adam Dunn delivered RBI singles while Coco Crisp recorded two hits and scored for the Athletics.

Chris Young (12-8) extended his winless string to four starts after yielding two runs and four hits while striking out five in six-plus innings for the Mariners, who remained one game behind Kansas City for the second wild-card spot. Austin Jackson snapped an 0-for-14 slide with two hits for Seattle, which had seven hits.

Fuld belted a 1-2 pitch out to right with one out in the first for his fourth home run of the season. Moss recorded his 24th homer and first since July 24 - a span of 39 games - when he belted a 2-0 fastball over the wall in right to give Oakland a 2-0 lead in the seventh.

The Mariners had runners at second and third with none out in the seventh before reliever Dan Otero retired Jackson on a grounder, struck out Michael Saunders and got Kendrys Morales to fly out after an intentional walk to Robinson Cano. The Athletics tacked on a pair of insurance runs in the eighth when Crisp doubled and scored on Fuld's single, and Dunn's RBI single plated Fuld.

GAME NOTEBOOK: Seattle won the season series 10-9. ... Dunn is 8-for-32 with two homers, seven RBIs and 12 strikeouts since being acquired from the White Sox. ... The Mariners, who remain one of two teams in the majors without a grand slam (Los Angeles Dodgers), fell to 29-19 versus left-handers this season.