SEATTLE -- Bob Melvin became the third manager to win 500 games in Oakland as the A's rolled to a 7-4 series-opening victory over the Mariners on Thursday night, helped by the first win for rookie right-hander Paul Blackburn and a three-run homer by Khris Davis.
Blackburn, who was traded from the Mariners to the A's in November for Danny Valencia, hurled 7 2/3 innings of one-run ball in his second big league start. The 23-year-old allowed eight hits with one walk and no strikeouts and has given up just one earned run over 13 2/3 innings to begin his big league career.
"He throws the ball where he wants to, mixes his pitches," Melvin said. "There's something to be said about that. It's not only about velocity. Really good performance from him. And we had no bullpen tonight, too. He needed to go deep for us."

After Davis went deep in the fifth, catcher Bruce Maxwell followed with his first home run of the season to give Oakland a 7-0 lead. Jed Lowrie also had a pair of RBIs with a first-inning double in his 2-for-4 night for the A's (38-48).

Valencia unloaded a three-run homer in the ninth to cut the final margin, but the Mariners (41-46) dropped their eighth straight home game, their longest losing streak at Safeco Field since May 2010. Shortstop Jean Segura went 4-for-4 with a double to hike his average to .354 and right fielder Mitch Haniger hit a solo homer in the fifth inning.
• Haniger emerges from slump with double, homer

Rookie right-hander Sam Gaviglio had been Mr. Steady for the Mariners in his first nine starts, but the 27-year-old allowed season highs with nine hits and seven runs in his shortest outing -- 4 2/3 innings -- as he fell to 3-4 with a 4.31 ERA. Yovani Gallardo threw 4 1/3 scoreless innings of relief with just one hit.
"We have to start playing better baseball," Mariners manager Scott Servais said. "Tough start tonight to the game. Tough start last night to the game. We've got to pick it up -- everybody, players, coaches, myself. We've got to get it going in the right direction."

MOMENTS THAT MATTERED
Pitcher's best buddy: Blackburn gave up hits in each of the first three innings, but faced the minimum, thanks to a trio of double plays. The first two were standard 4-6-3's. But in the third inning, after Haniger led off with a double, rookie center fielder Jaycob Brugman threw out Haniger at third as the rookie tried to tag and advance on a flyout by Jarrod Dyson. More >
"That's a really good throw by Brugman," Melvin said. "He's been working hard on his defense out there, got behind it where he had something behind the throw. And Haniger looked like he ran into a fire hydrant with [third baseman Matt] Chapman over there. The double plays really allow a pitcher to breathe a little bit and know you can throw the ball over the plate, keep it on the ground and he's going to get some outs."

Khris with a K: Davis has been striking out at a high rate and his two whiffs in his first two at-bats gave him 115 on the season, breaking the A's record for strikeouts before the All-Star break: 114, set by Jack Cust in 2008. But when Davis hits 'em, well, his three-run opposite-field blast in the fifth broke the game open and gave the 29-year-old slugger 24 home runs and 60 RBIs on the season. The 24 homers are the most by an A's player before the break since Mark McGwire hit 31 in 1997.
"We've seen him do that all the time. We've seen him hit 'em 20 rows up over there," Melvin said. "As soon as you see him hit one in that direction like that, you always think it will go out of the ballpark. We're sort of spoiled to see him do that all the time."

QUOTABLE
"We'll see. Obviously we have a lot of season ahead of us. It's nice to see he's continuing to work and taking his craft seriously. He is a veteran guy and he's not packing it in, by any means. He knows he still has a valuable role on this club and I certainly appreciate what he did tonight." -- Servais on whether Gallardo has a chance to work back into the rotation after allowing just one earned run in 10 1/3 innings since moving to the bullpen
SOUND SMART WITH YOUR FRIENDS
Segura is 10-for-14 over his last three games for Seattle and his four games with four-plus hits this season is tied for second in the Majors, behind only the five by Boston's Mookie Betts, despite having spent a month on the disabled list.

UPON FURTHER REVIEW
The A's challenged a play on Maxwell's single in the fourth inning, arguing that a fan interfered with the ball as it rolled down the left-field line. The replay crew overturned the ruling and determined the fan did interfere with the play, but Maxwell remained at first because the replay official deemed that Maxwell wouldn't have made it past first even without the fan interference.
"I have no idea [on what happened]," Maxwell said. "I was just trying to get to first base. I'm not the fleetest of foot. … I don't think there was enough fan interference to make a difference there. Even if he doesn't hit that ball, it still is going to hit that catty corner there and I'm still going to be at first base."

WHAT'S NEXT
A's:Sean Manaea (7-4, 3.75 ERA) toes the rubber for the 7:10 p.m. PT start in the second of a four-game set. The left-hander is pitching well as of late, with a 6-1 record and a 2.84 ERA in his last nine starts.
Mariners:James Paxton (6-3, 3.27 ERA) gets the ball for Friday's 7:10 p.m. PT game against the A's. The lefty is 3-3 with a 5.15 ERA in seven starts since coming off the DL, but is coming off a strong outing in which he had a perfect game for 5 1/3 innings and wound up allowing one run on two hits over 6 1/3 frames in Anaheim.
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