SEATTLE(AP) The Mariners might have taken a step toward a more stable rotation next season based on Brandon Morrow 's effort against Oakland.

Morrow allowed one hit over eight impressive innings and Ken Griffey Jr. hit a three-run homer, sending Seattle to a 7-0 victory over the Athletics on Wednesday night.

''I don't know if we've had a better-pitched start all season,'' Mariners manager Don Wakamatsu said. ''You can put that up there with any of the top ones.''

Griffey's 629th career home run came in the first inning. Morrow (2-4) yielded only an infield single to Rajai Davis in the fourth.

Davis hit a high-hop grounder up the middle and shortstop Josh Wilson ranged far to his left to snag the ball behind the bag. Wilson made a running, off-balance throw to first baseman Jack Hannahan , who scooped it on one bounce. But the speedy Davis clearly beat the throw.

Cy Young Award contender Felix Hernandez , who is 18-5 with a 2.48 ERA, has established himself as the ace of Seattle's staff. The problem for the Mariners has been finding solid starters behind him.

Jarrod Washburn was traded to Detroit. Erik Bedard and Carlos Silva got injured. Ryan Rowland-Smith spent most of the season at Triple-A Tacoma to sort out his delivery.

Morrow, selected fifth overall in the 2006 amateur draft, began the season as the team's closer but shifted to starter, ultimately failing to secure his spot. He also spent much of the season with Tacoma trying to find his rhythm.

''A lot of credit needs to go to our minor league system and also (pitching coach) Rick Adair,'' Wakamatsu said. ''This gives us a lot of hope going into next year for him.''

Morrow threw 105 pitches in the longest start of his career. He tired in the eighth, issuing consecutive two-out walks to Eric Patterson and Travis Buck . Morrow then got Cliff Pennington on a fly to right.

Morrow also set a career high for strikeouts with nine. Previously, his best outing was his first career start on Sept. 5, 2008, when he held the Yankees to one hit over 7 2-3 innings in a 3-1 victory.

''Everything he threw was around the plate,'' Oakland's Daric Barton said. ''He pretty much dominated the zone. At one point he threw 46 strikes and 16 balls. He was throwing everything for strikes - curveball, fastball, changeup, in and out.''

Shawn Kelley worked the ninth, allowing a two-out single to Landon Powell . It was the fourth time Mariners pitchers have held the opponent to two hits or fewer.

''In all areas, I've improved since the beginning of the year,'' Morrow said. ''I'm going to get that game on DVD and watch it about 20 times. It's a great way to finish the year after a rough year, especially the beginning of the year.''

Adam Moore , who entered in the second after catcher Kenji Johjima was hit on the left elbow with a pitch, had a solo shot in the fourth. It was his first career home run and he became the 22nd Mariners player to go deep this season, a club record.

Moore, a September call-up, caught most of Morrow's games at Tacoma.

''He was lights out tonight,'' Moore said. ''He was going right at these guys with every pitch he had. That was the Brandon I caught a lot in Tacoma.''

Morrow was sent down to the minors during the All-Star break.

''He wasn't bitter. He wasn't anything. He was just down there competing, getting his command back,'' Moore said. ''He can be a great pitcher in this league. Tonight, he went out and showed it.''

Griffey hit his second home run in two nights and his 18th this season. It traveled an estimated 421 feet to straightaway center, just his second to center field this season. The drive came off Clayton Mortensen (2-4), the 407th pitcher Griffey has homered against in his career.

''I was thinking back up the middle,'' Griffey said. ''I was looking for a pitch to hit and hit it hard.''

Mortensen, making his seventh big league appearance, threw 55 pitches in his one inning plus three batters.

''You know the name, you know who he is,'' Mortensen said. ''It doesn't play a huge role, but when he steps in the box it's, 'Oh, I got Ken Griffey Jr. to face now.'''

It was the third time Oakland has been held to two hits this season. It also was the ninth shutout against the A's and the 10th for the Mariners.

NOTES: Wakamatsu, uncertain if Sunday's game will be the final one for Griffey, is considering playing him in center field. ''It would be nice to finish it that way,'' Wakamatsu said. ''But I want to honor his wishes, too.'' Griffey has played four games in left field this season, three in right and none in center. His last game in the field was June 30 at New York. ... Mariners 1B Russell Branyan (herniated disk) and SS Jack Wilson (bruised right heel) probably won't play again this season. ... Oakland OF Scott Hairston (hip, back) is out for the season.