(Photo credit: Stephen Brashear-Imagn Images)

For the Seattle Mariners, it was another lost opportunity in a 50th anniversary season full of them.

The defending American League West champions, who fell one game shy of reaching their first World Series last fall, opened what was supposed to be a season-defining stretch with a 7-4 defeat to the lowly Athletics on Thursday night.

The teams' four-game series will continue Friday night in Seattle.

It was the way the Mariners (66-75) lost on Thursday that led to several fans booing them after the final out.

The Mariners struck out a season-high 18 times, went 4-for-16 with runners in scoring position and left 14 on base -- including multiple runners in seven innings -- against a team with the worst ERA in the major leagues.

'We had opportunities early, we just didn't cash in, and then as we got into their bullpen, we just weren't able to find barrels in those situations,' said Mariners manager Dan Wilson, whose team fell six games behind division-leading Houston and 4 1/2 games out of the final AL wild-card spot with 21 to play. 'And that's what you need to do. Sometimes you start to look for too much in those situations, and you get away from what you do.'

The Mariners batted around and scored three runs off A's starter Jack Perkins in the first inning but easily could have had more. Perkins struck out the side -- all on pitches out of the strike zone -- including rookie Brock Rodden on a checked swing with two outs and the bases loaded.

Perkins somehow lasted three innings without allowing another run despite issuing seven walks.

'We had him on the ropes for sure, whether it was the first or second inning,' Wilson said. 'We had a chance to add on to the lead and give us what we needed to keep going. But he was able, one way or another, to wriggle out of it. And it cost us.'

The Athletics' beleaguered bullpen gave up one run over six innings and struck out 11. Scott Blewett got the victory with two scoreless innings in which he fanned four.

'Blewett was outstanding. I think that was probably the big turning point in the game, for him to come in the fourth inning and be able to give us two scoreless and give our offense a chance to get back in the game,' A's manager Mark Kotsay said. 'We took the lead. He went back out and held that.'

Zack Gelof and Donovan Walton homered for the A's (55-86).

Mariners prized prospect Kade Anderson, 22, suffered his first major league loss. The left-hander allowed four runs on seven hits over five innings.

'I don't think it holds up to the standard that I put on myself, and my team has put on me,' Anderson said. 'Just really unacceptable tonight, and I look forward to getting out there (again).'

Friday's game is scheduled to feature a pair of right-handers in A's rookie Kade Morris (0-1, 9.82 ERA) against Seattle's Logan Gilbert (11-8, 3.42).

It will be Morris' first start since his June 6 MLB debut, when he allowed nine runs over four innings of a 13-2 loss in Houston. He has made four relief appearances since. This will be his first time facing the Mariners.

Gilbert had a three-start winning streak snapped with a 7-0 loss Sunday in Toronto, when he gave up three runs over five innings. He is 5-1 with a 2.81 ERA in 16 career starts against the A's.

--Field Level Media