OAKLAND, Calif. (AP) -- The fired-up Oakland Athletics came out swinging, and Chris Young's day was short-lived.
Newcomer Adam Dunn hit a two-run homer as Oakland jumped to a five-run lead in the first, and Young failed to make it out of the inning as Seattle lost 6-1 to the Athletics on Monday.
"I wasn't sharp. My stuff wasn't good, it was flat," Young said. "They came out super-aggressive, you could see it. They were motivated. I didn't have it. When I take the ball I expect to perform."
He didn't have much help in the shortest start of his career on a day the A's were desperate to bounce back from an awful road trip.
Acquired a day earlier in a trade with the Chicago White Sox, the 6-foot-6, 285-pound Dunn immediately became an imposing presence in the middle of Oakland's order. Dunn is the 12th player in Oakland history to homer in his first at-bat with the team.
A 14th-year major leaguer who has never played in the postseason, Dunn was a welcome sight for a team that just got swept in a four-game series by the AL West-leading Los Angeles Angels and was shut out for 29 straight innings.
"That's the most excited, anxious, probably call it a little nervous, than I've been in a long time," said Dunn, who was thrown off by the celebratory tunnel formed by teammates in the dugout.
Another recent acquisition, Geovany Soto, added a two-run single with two outs in the first that chased Young (12-7) for the shortest start of his career.
The A's broke loose a day after manager Bob Melvin let them have it in a closed-door team meeting. He called his team's play "embarrassing and "pathetic" after the A's totaled just four runs in the sweep at Anaheim.
"They ran the opening kickoff back for a touchdown and the game was over," Mariners manager Lloyd McClendon said. "It wasn't our day."
Taijuan Walker pitched six solid innings of relief after Young's quick exit.
"I needed to step up," Walker said. "They told me to be ready."
Brad Miller homered leading off the sixth for Seattle, which came into the series opener as the American League's top road team.
Dunn went 2 for 3 batting cleanup as the designated hitter. He provided a nice lift for an Oakland offense that has struggled since dealing Yoenis Cespedes to Boston for Jon Lester on July 31.
With 461 career home runs, Dunn tied Red Sox star David Ortiz for 35th place on the all-time list.
Dunn quickly staked Jason Hammel (2-5) to a lead. Hammel also started the season in Chicago, and was traded by the Cubs in July.
A sellout crowd of 36,067 saw the A's win after a stretch in which they lost five of six.
Robinson Cano's 21-game hitting streak against the A's ended. It dated to Sept. 22, 2012.
Mariners: OF Michael Saunders, on the disabled list since July 11 with a strained left oblique, reported to Arizona to work on strengthening and get some at-bats in simulated games before the club determines the next step in his rehab.
Athletics: CF Coco Crisp will have more trigger-point injections for neck stiffness after colliding with the outfield wall Friday. He hit batting practice right-handed. C John Jaso (concussion) swung in the indoor cage and hopes to hit outside Tuesday.
Mariners: LHP James Paxton (4-1, 1.83) makes his first career appearance against the A's as he looks to win his second straight start. Paxton is 7-1 with a 1.71 ERA in 11 career starts.
Athletics: RHP Sonny Gray (13-7, 3.03) is 4-0 with a 1.10 ERA in his first five starts against Seattle, his most victories against any team.
Mariners: Placed 1B-DH Jesus Montero on the suspended list. The 24-year-old Montero was recalled from his rehabilitation assignment Friday following a verbal altercation with a Mariners scout at a Class A Northwest League game. ... September call-up RHP Carson Smith made his major league debut in the eighth. He threw two pitches and retired Josh Donaldson on a grounder.
Athletics: Reinstated SS Jed Lowrie from the 15-day disabled list and he singled in his first at-bat since Aug. 13. He suffered a hairline fracture of his right index finger Aug. 4.