Athletics 6, Mariners 1: Adam Dunn homered in his first at-bat with Oakland and Jason Hammel was dominant through eight innings as the host Athletics snapped a four-game slide.After scoring only four runs in being swept four straight against the American League West-leading Los Angeles Angels, Oakland scored five times in the bottom of the first and rode Hammel to pull within 4 1/2 games of the idle Angels. Hammel (10-10) yielded a run and three hits with five strikeouts as the wild-card leading Athletics moved 5 1/2 ahead of Seattle.Geovany Soto had two RBIs, Josh Reddick was 2-for-4 with two runs scored and Eric Sogard chipped in two hits and an RBI for Oakland. Brad Miller belted a solo homer in the sixth for Seattle, which fell 1 1/2 games behind Detroit in the race for the second wild-card spot.Reddick doubled with one out in the first and Dunn - acquired Sunday in a trade with the Chicago White Sox - smacked his 21st of the year to give the Athletics a quick 2-0 lead against Chris Young (12-7), who lasted two-thirds of an inning in the shortest start of his career. Oakland then loaded the bases on two walks and a single before Soto brought in a pair with a base hit to left and Sogard made it 5-0 with a single.Hammel retired the side in order in the first, third and fourth innings before Miller deposited a 1-0 offering over the wall in right to get the Mariners on the board leading off the sixth. Hammel retired the final nine men he faced, striking out the final two, to pick up his second win in nine appearances since joining Oakland.GAME NOTEBOOK: Dunn's 461st career homer made him the 12th player to hit a home run in his first at-bat with Oakland. ... Young was charged with five runs on four hits and two walks while top pitching prospect Taijuan Walker, who was brought up as part of September call-ups, allowed a run in six innings of relief. ... The top four spots in Seattle's lineup went a combined 0-for-15.