OAKLAND, Calif. -- Hitting home runs at the cavernous Oakland Coliseum, especially on cool Bay Area nights, is supposed to be hard, but Khris Davis keeps making it look easy for the Oakland Athletics.

Davis hit his career-high 28th home run Friday night, helping the A's snap the Seattle Mariners' six-game winning streak with a 6-3 victory.

Davis, who had 27 home runs last season for the Milwaukee Brewers, set a career high with a two-run blast in the first inning when the A's built a 3-0 lead. He had two hits and scored twice.

"It's definitely a goal of mine to get better every year," said Davis, who leads the A's with a career-high 72 RBIs. "I'm glad first and foremost that the team won. I can enjoy it for a night, but I also have more work to do."

Davis has hit 15 of his home runs in Oakland and 23 overall at night. Many of his blasts have gone the opposite way, and he homered off Mariners right-hander Joe Wieland down the right field line.

"He's got the most power to right field that I've seen," said A's shortstop Marcus Semien, who went 4-for-4, matching his career high for hits. "Wherever the pitch is, he's trying to hit it there. He knows he can hit it out of the park anywhere, so that's a special gift to have."

Semien also scored two runs for the A's, who won for the fourth time in their past five games. Stephen Vogt had two hits and an RBI double, and Yonder Alonso went 2-for-4 and drove in two.

Manaea (4-7) allowed three runs and three hits, struck out four and walked three. He won for the first time since June 29 against San Francisco, ending a 0-3 skid in his previous seven appearances, including six starts.

Manaea had a no-hitter through four innings with three double plays and three walks. He gave up a home run for the fourth straight game and has allowed six homers in that span.

"It just wasn't coming out of my hand well, but I felt like I did an OK job pushing through it and battling and just getting outs," Manaea said.

Kyle Seager hit his 22nd home run of the season for Seattle, a solo shot in the fifth. Shawn O'Malley went 2-for-3 with an RBI triple and a walk and scored a run.

"We didn't do a whole lot offensively," Mariners manager Scott Servais said. "It was like Groundhog Day, double play, double play, double play the first three innings."

Wieland (0-1) was called up from Triple-A Tacoma and started against Oakland in his Mariners debut. He gave up six runs and nine hits in five innings with three strikeouts and no walks.

A's reliever Liam Hendriks pitched a perfect seventh with three strikeouts, Ryan Dull a scoreless eighth and Ryan Madson a perfect ninth for his 25th save of the season.

After spotting the A's a 3-0 lead in the first, the Mariners scored a run in the fifth on Seager's home run and two in the fifth. Ketel Marte hit a leadoff single and scored on O'Malley's triple to center. Franklin Gutierrez brought O'Malley home with a sacrifice fly.

The A's answered with three runs in the sixth when they opened the inning with consecutive singles by Semien, Vogt, Davis, Alonso and Danny Valencia. Alonso drove in two runs and Valencia one in the inning.

Semien had four hits for the third time in his career.

"It felt great," Semien said. "I hit four balls pretty hard. That's the goal every night. It's not going to happen every night, but you work hard every day in the cage and (batting practice) to do that."

Semien lined a single to left with one out in the first inning and scored on Vogt's double down the right field line. Davis followed with an opposite-field, two-run blast to right field, launching Weiland's 1-0 pitch.

"There were some nerves," Wieland said. "The first couple pitches I was trying to get settled in. After that it was just another start. Semien got that hit, Vogt hit a good pitch off the plate. Davis hit a good pitch, down and away."

Seager homered with two outs in the fifth, pulling Manaea's 3-2 fastball down the right-field line and cutting Oakland's lead to 3-1.

NOTES: Oakland LHP Sean Doolittle (strained left shoulder) threw 20 pitches in a simulated game Friday and is nearing a rehab assignment, Athletics manager Bob Melvin said. ... Seattle LHP James Paxton (left elbow contusion), who was hit by a line drive Sunday against the Los Angeles Angels, still isn't throwing pain-free, but manager Scott Servais said he's hopeful that Paxton can return to the rotation Tuesday or Wednesday. ... Mariners RHP Steve Cishek (left hip labrum tear) has resumed throwing bullpen sessions and is close to going on a rehab assignment, Servais said. ... A's RHP Jesse Hahn (strained right shoulder) will throw his first bullpen session Saturday since going on the 15-day disabled list Aug. 5. If all goes well, Hahn will make one rehab start then return to the A's, Melvin said. ... The Mariners designated Triple-A Tacoma OF Daniel Robertson for assignment, opening a spot on the 40-man roster for RHP Joe Wieland, who was called up from Tacoma and started against the A's. ... Philadelphia claimed LHP Patrick Schuster off waivers from Oakland. Schuster was designated for assignment Wednesday.