Casper Wells hit a go-ahead, three-run double with two out in the seventh inning and the Seattle Mariners beat the slumping Baltimore Orioles 6-3 on Monday night.

Miguel Olivo and Dustin Ackley added back-to-back homers in the eighth as the Mariners rallied for the win in their first game of the season against Baltimore.

Wells had a chance to drive home a run earlier in the game and failed. But he came up in the eighth and drove an 0-1 pitch from Jason Hammel (8-4) into the gap in right-center. Ackley, Munenori Kawasaki and Ichiro Suzuki all scampered home to give Seattle a 4-3 lead.

Wells picked up his first RBIs since June 20 at Arizona. He struck out with a runner on second in the third inning.

Olivo hit his seventh homer against Troy Patton and Ackley drove the next pitch over the wall in right for his fifth of the season. It was the second set of consecutive homers this season for Seattle.

Chris Davis hit a three-run shot off Mariners starter Hisashi Iwakuma in the fourth, but that accounted for all of Baltimore's offense. After Davis' 14th homer, the Orioles got just three baserunners against Iwakuma, Steve Delabar (2-1), Shawn Kelley and Tom Wilhelmsen.

The Orioles have lost six of seven.

Ackley started the seventh with a walk and stole second when Hammel struck out Chone Figgins on a 3-2 pitch. Ackley advanced to third on Kawasaki's single, but Brendan Ryan fouled out when catcher Matt Wieters made the catch at the edge of the top step of the Mariners' dugout. Suzuki walked to load the bases and Wells followed with a liner that cleared the bases.

The six runs were the most scored at home by the Mariners since June 16.

Seattle took a 1-0 lead in the third when the unlikely trio of Figgins, Kawasaki and Ryan — none of whom entered the night hitting higher than .186 — combined to plate the first run. Figgins led off with a single, moved up on Kawasaki's sacrifice and scored on Ryan's single to center.

Ryan was stranded at second and Seattle wasted another opportunity in the sixth. Wells' one-out single was followed by John Jaso's double that should have been caught by Steve Pearce in left, but glanced off his glove. With runners at second and third, Kyle Seager hit a tapper in front of the plate and Olivo struck out.

The Mariners were able to hang around thanks to their bullpen. Delabar worked two innings, striking out three and allowing one baserunner. Kelley struck out a pair in the eighth and Wilhelmsen worked the ninth for his seventh save in eight chances.

Iwakuma was making a spot start with Kevin Millwood still nursing a sore groin that has twice forced him to leave starts early in the past month. Iwakuma threw five innings, giving up just three hits. But he made the one critical mistake to Davis on a 1-0 pitch.

Davis has made a point of picking on Mariners pitching, first when he was with Texas and now Baltimore. Davis came into Monday night hitting .314 with six homers, seven doubles and 14 RBIs in 29 career games against Seattle. He also doubled in the second inning off the wall in left, missing a homer by just a couple of feet.

NOTES: The Mariners had three Japanese players in the starting lineup — Suzuki, Kawasaki and Iwakuma — for the first time in major league history. ... Seattle signed first-round draft pick C Mike Zunino. Zunino was taken with the No. 3 overall pick in June's amateur draft. He will be introduced at a news conference on Tuesday. ... Newly acquired Baltimore DH Jim Thome had his first hit with the O's in the fourth inning.