SEATTLE — Rich Harden allowed three singles and struck out seven in seven innings to lead the Oakland Athletics to their first win of the season, a 9-0 victory over the Seattle Mariners on Wednesday night.

Mark Ellis, batting in the ninth spot in the order, drove in five runs — and seven in the final two games of the series — as the A’s avoided their first 0-3 start since 1996.

The night was more reminiscent of last season, when Oakland went 17-2 against Seattle, than the previous two games. The Mariners were emphatically denied their first 3-0 start in 12 years.

And it was very reminiscent of how Harden masters the M’s — and many others.

He has allowed seven earned runs in 10 career games against Seattle. That’s an ERA of 1.28. He’s 5-0 with a 0.86 ERA in six starts at Safeco Field, which is a few hours drive and a ferry ride from his native Victoria, British Columbia.

The A’s haven’t lost a regular-season game that Harden has started since Aug. 14, 2005, against Minnesota — and he allowed just a solo home run in eight innings of a 2-1 loss that day. Of course, the 25-year-old Canadian pitched in just nine games during 2006 because of a strained back and a sprained elbow.

But those pains looked light years ago Wednesday.

Harden (1-0) continually and easily fired fastballs past the flailing Mariners. He didn’t allow a hit until Ichiro Suzuki’s single leading off the fourth. He had only two three-ball counts — on both of his walks, to Jose Vidro in the fourth and Suzuki in the sixth. Manager Bob Geren gave him a hearty handshake for a job well done at the top step of the dugout after the bottom of the seventh.

Rookie Jay Marshall pitched a scoreless eighth, and closer Huston Street threw a perfect ninth in his first appearance of the season.

Miguel Batista’s Mariners debut was miserable, allowing eight runs and 10 hits and balking twice in 42⁄3 innings.

The eighth run walked home. Mike Piazza scored on Batista’s first balk, when the 36-year-old former Arizona Diamondback started and then stopped his throwing motion during Oakland’s five-run second inning.

Piazza had reached on a single to lead off the decisive inning, his first hit as an AL player after seven at-bats. Eric Chavez then doubled before Batista’s 0-2 pitch to Bobby Crosby grazed Crosby’s jersey. Batista, one of Seattle’s three new starters, followed that gaffe by walking rookie Travis Buck to load the bases for Ellis.

Two pitches later, Ellis drove a thigh-high fastball to the wall in left-center field to score all three runners to put Oakland ahead 4-0. Milton Bradley’s single then scored Ellis to make it 5-0.

Bradley added an RBI double in the fourth. Ellis then tied his career high with his fourth and fifth RBIs with another ringing double in the fifth inning, on Batista’s final pitch. Sean White relieved for his major league debut — and hit Shannon Stewart with a pitch. Stewart tacked on a ninth run on Nick Swisher’s single.

Notes: Buck, a native of Richland, Wash., playing in his second game in front of family, struck out three times. ... The Mariners gave SS Yuniesky Betancourt a three-year contract extension, with a club option for 2012, one day after he hit the tiebreaking home run late in an 8-4 win.