SEATTLE — Dylan Moore hit a two-run homer off Oakland starter Paul Blackburn and finished with a career-high five RBIs to help the Seattle Mariners beat the Athletics 8-1 on Friday night.

Dating back to the start of last season, the A’s loss was their 13th in 14 games against the Mariners and their fifth loss in six games overall.

“Moore seems to be kryptonite for us,” A’s manager Mark Kotsay said. “Every time he’s in the lineup, it seems like we have trouble getting him out.”

While the Mariners rebounded to open a brief homestand after losing three of four in Minnesota, the immediate concern was the status of starting pitcher and Alameda native Bryan Woo, who left with one out in the fifth inning.

Making his first start of the year after being slowed by a sore elbow during spring training, Woo, 24, allowed just one hit through the first four innings only to leave the game after getting Tyler Soderstrom to foul out behind third base to open the fifth.

Catcher Cal Raleigh immediately went to the mound and was quickly joined by pitching coach Pete Woodworth and manager Scott Servais. Woo eventually walked off the mound alongside athletic trainer Kyle Torgerson and was replaced by Trent Thornton.

Servais told reporters that Woo will make his next start, saying he just got tight while sitting during the Mariners’ five-run fourth inning.

Woo was expected to be the No. 5 starter in Seattle’s rotation entering the season before the elbow soreness emerged in spring training. In 11 1/3 innings over three rehab outings with Triple-A Tacoma, Woo didn’t allow an earned run. Last season, Woo was 4-5 with a 4.21 ERA in 18 starts with the Mariners.

“I was just sitting for a long time and it’s hard to get it going again,” said Woo, an Alameda High alum who allowed one hit, struck out three, walked one, and threw 62 pitches Friday. “It’s been a theme through the rehab process. Pretty normal.”

After cruising through the first three innings, Blackburn (3-2) ran into trouble immediately in the fourth, walking Mitch Haniger and Cal Raleigh.

Luke Raley barely missed a three-run homer and settled for an RBI double off the top of the wall. Ty France lined a two-run double, and Moore hit his third homer of the season just inside the foul pole in left.

Moore followed an inning later with a two-out, two-run single to give the Mariners a 7-0 lead. He added an RBI single to score Raley in the seventh.

Thornton (1-1), Kirby Snead, and Cody Bolton kept the Mariners’ shutout of the A’s going until the ninth, when Lawrence Butler’s two-out RBI single off Austin Voth plated Oakland’s only run.

Blackburn was tagged for all seven runs and was roughed up for a second time in three starts after giving up six earned runs over four innings to Baltimore on April 28. In his other five starts this season, Blackburn has allowed eight earned runs in 38 innings pitched.

“Just kind of one of those days, I guess,” Blackburn said. “In the fourth, obviously starting off with those two walks is not ideal. Not really setting us up for a good inning there.”

TRAINER’S ROOM

Athletics: IF Zack Gelof (oblique) will be in the lineup for Triple-A Las Vegas on Saturday as he begins a rehab assignment. Gelof has been out since late April.

UP NEXT

Athletics: RHP Joey Estes is expected to be recalled from Las Vegas to make his first start of the season. Estes made two starts last September, including one against Seattle when he allowed five runs in 4 2/3 innings.

Mariners: RHP Bryce Miller (3-2, 2.61) has pitched at least six innings of five of seven starts this season and has yet to allow more than four earned runs.