ST. PETERSBURG -- Coming off a convincing weekend sweep of the Red Sox that moved them into first place in the American League East -- including two games in front of the largest home crowds of the season and one on national television -- the Rays had plenty of momentum on their side heading into Monday night’s matchup with the Mariners at Tropicana Field.

But after a couple of high-intensity series, Tampa Bay’s opener against Seattle turned out to be a letdown. Starter Michael Wacha gave up six runs in four innings, and the Rays struggled to get anything going offensively as their four-game winning streak ended with a flat 8-2 loss to the Mariners before a crowd of 5,855. The defeat dropped Tampa Bay’s (64-43) AL East lead over the idle Red Sox  (63-44) to one game.

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“We couldn't create any momentum for ourselves,” said Rays center fielder Kevin Kiermaier, whose fifth-inning triple was one of Tampa Bay’s few highlights on the night. “They had better at-bats from the get-go, and even when we were down five or six, it seemed like a lot more than that just because we weren't able to generate a whole lot.

“They were the better team today all around. We’ll just learn from this one, come out tomorrow and try to bring a little bit more energy and tempo.”

As good as they’ve been all season, the Rays have struggled to solve the Mariners. Seattle has beaten Tampa Bay five times in five meetings this season, securing a four-game sweep at T-Mobile Park from June 17-20, then bouncing back from consecutive walk-off losses in Texas over the weekend to win Monday night. Since Aug. 19, 2019, the Rays have lost seven of eight games against the Mariners.

Nobody on either side of the field could pinpoint a reason why the Mariners have held the upper hand against the Rays, but it’s hard to argue with their recent history.

“All of us, I think, just kind of had an off night. And Seattle, they've kind of had our number,” Rays manager Kevin Cash said. “We're going to have to make some adjustments moving forward. They've played really well against us.”

The Rays scored 33 runs and hit 10 homers during their four-game winning streak, and they have been one of the Majors’ best offensive teams since the All-Star break. But Mariners starter Chris Flexen held them to two runs on seven hits and two walks over 6 2/3 innings.

Randy Arozarena hit his fifth homer of the season out to center in the fourth, then Kiermaier tripled and scored on a groundout in the fifth. That was the extent of the Rays’ offense, as they only had three at-bats -- and no hits -- with runners in scoring position.

“We feed off energy, off each other, through great at-bats and big innings, and we just weren't able to piece those things together tonight,” Kiermaier said. “I don't know what it is about the Mariners, but they've had our number. We're going to do everything in our power to change that these next two games versus them, so we'll see what we're about.”

Wacha, meanwhile, continued his up-and-down season. Facing the Yankees on Wednesday, the veteran right-hander struck out nine while allowing just one unearned run over five innings. Looking back at that performance Monday afternoon, Cash stated, “Let's bottle it up and go do it again.”

But Wacha could not recapture that form, lacking finish to his pitches and struggling to get ahead in counts. And after he stranded runners in each of the first two innings, the Mariners eventually took advantage. The first seven hitters reached base safely in what Wacha accurately summarized as a “frustrating” five-run, 42-pitch third inning, reminiscent of his four-run first frame in Seattle on June 18.

“It was very familiar,” Wacha said. “They put up some good ABs. They laid off some tough pitches, and then got one that they could handle that was over the plate and it found a hole. That's kind of baseball. Sometimes they're hitting them at people. Some days, they're finding the holes. And they definitely found the holes.”

By the time the inning came to an end, the Rays found themselves in an unfamiliar position: down and out, unable to come back like they so often have this season.

“It's one game, so no one's worried about it or anything,” Kiermaier said. “We just had a great weekend. These things happen. They were the much better team tonight, and it showed.”