SEATTLE — Danny Valencia believed all along that he just needed the opportunity to show what he could do.
The Oakland A's are now believers.
Valencia, picked up on waivers Aug. 3 from Toronto, hit a two-run homer in the eighth inning that lifted the Athletics over the Seattle Mariners 4-2 Friday night.
"We put him in the four-hole the first day and he had an impact on the first day," A's manager Bob Melvin said. "He hit a homer and has been sitting in that spot ever since."
"He's been real consistent. We really had planned on playing him against lefties. All he's done is hit off lefties, righties and everyone else."
Valencia has 34 RBIs in 45 games with the A's. That's the most RBIs in franchise history for a player who's played fewer than 50 games.
"It was unexpected coming here. But having said that, they gave me the opportunity to play every day," Valencia said. "They put me in the cleanup spot and I've been able to reward them for it."
"I've been playing the past few years waiting for this opportunity and finally it's come. I'm happy to take advantage of it," he said.
Josh Reddick opened the eighth with a single off reliever Danny Farquhar (1-8). Valencia, who had three hits, followed with his career-high 17th homer deep into the left-center field bleachers. He's homered 10 times for the A's.
"It was about eight inches over the zone, 1-2 fastball and he found it," Farquhar said.
Said Valencia: "It was definitely a ball. I told myself to shorten my swing and just punch it. Sometimes you do things and can't explain how it got done."
Aaron Brooks (3-4), who gave up two runs and six hits over seven innings, earned the victory. Sean Doolittle finished for his fifth save in six opportunities.
Hisashi Iwakuma pitched seven innings for the Mariners in a no-decision. He allowed one earned run and nine hits, striking out eight and walking none.
Iwakuma, who ended the season at 9-5, is the fifth pitcher since 1961 to open his career with at least a .625 winning percentage in each of his first four seasons. He joins Dwight Gooden (1984-91), Roy Oswalt (2001-08), Tim Hudson (1999-04) and Teddy Higuera (1985-88).
"It was a tight ballgame and I knew it," Iwakuma said through a translator. "As the game started, they battled every at-bat and got my pitch count up. At the end, it's unfortunate that we lost, but I was able to pitch my game."
Brad Miller had three hits for the Mariners, including his 11th home run, a solo shot in the fifth.
Robinson Cano, who said before the game that he would have sports hernia surgery later this month, singled in the Seattle fifth to extend his hitting streak to a season-high 14 games. He is hitting .357 during the streak.
A's: Oakland put 23 players on the disabled list this season, up from 18 last year.
A's: LHP Sean Nolin (1-2, 5.25) has a 0-1 record and a 9.82 ERA over his past two starts. He is 0-1 with a 5.14 ERA in a pair of career starts against Seattle.
Mariners: LHP Roenis Elias (5-8, 3.89) has a 2.05 ERA over his last four starts with just one victory. That's his only win since June 19. Against the A's, he is 1-1 with a 3.44 ERA in four career appearances.