DETROIT -- Kyle Seager left Comerica Park with the first three-homer game of his career and he had no idea how it happened.
"I don't remember ever hitting three in a game at any level,'' he said. "I'm not sure I've ever done it.''
It was the 13th three-homer game in Mariners history. The last to accomplish the feat for Seattle was José López on Sept. 22, 2010.
Seager's first two homers were routine, but he got some help on the third one. His line drive to left-centerfield didn't have the distance to clear the fence, but center fielder Niko Goodrum and left fielder Brandon Dixon collided on the warning track. The ball hit Goodrum's glove and bounced over the fence.
"I was running, so I didn't see it,'' Seager said. "Everyone told me they knocked it over, but I'm going to have to find a replay online. When I tell the story, it's going to be a no-doubter.''
Seager and Tom Murphy hit back-to-back homers in the fourth and sixth innings, but Tigers reliever Jose Cisnero walked Murphy in the ninth. No teammates have ever hit back-to-back homers three times in one game.
Still, it was the first time the Mariners had the same pair of teammates go back-to-back multiple times in a game since May 2, 2002. Bret Boone and Mike Cameron did it twice in the first inning that day.
"That was a lot of fun,'' Murphy said. "I've never been a part of anything like that.''
The Mariners won for the second time in 10 games, improving to 5-0 against Detroit this season. Zac Grotz (1-0) picked up his first win with 1⅔ innings of relief.
Detroit lost for the ninth time in 12 games and fell to 16-42 at home. They need to go 6-17 in their final 23 games at Comerica Park to avoid becoming the first team to lose 60 home games.
Matthew Boyd (6-9) gave up seven runs and seven hits in 5⅓ innings. He gave up four homers, and has allowed 30 this season, the third-highest total in the majors.
"I take full responsibility for what happened -- that game is on me,'' Boyd said. "I made a few bad pitches and they hit home runs in some big situations. I have to be better than that.''
The Mariners took a 1-0 lead in the third on J.P. Crawford's RBI single.
Miguel Cabrera's ground-rule double tied the score in the bottom of the inning, but the Mariners regained the lead in the fourth.
Boyd retired the first two batters, but Seager and Murphy hit their first set of back-to-back homers to give Seattle a 3-1 lead.
"He just made some bad pitches,'' Tigers manager Ron Gardenhire said. "He's misfiring right now.''
"He has to execute pitches, not throw the ball down the middle,'' Mariners manager Scott Servais said. "This is on him -- he's pitched a long time and he knows what he needs to do.''
Kikuchi got only one out in the inning before leaving with runners on second and third. The Mariners walked Cabrera to load the bases, but Grotz's wild pitch made it 5-3.
Jordy Mercer's RBI double gave the Tigers a 6-3 lead, but the Mariners answered with a six-run sixth that included Seager and Murphy's second set of back-to-back homers.
Seager's three-run homer tied the score and Murphy followed with a long homer to left to put the Mariners up 7-6. Nick Ramirez replaced Boyd, but gave up two more runs without getting an out.
Goodrum and Dixon's collision came three innings after they pulled up to avoid each other, allowing a ball to fall between them.
In both cases, Gardenhire felt Goodrum was at fault. Goodrum has started games at seven infield and outfield positions this season but had played only three full games in center field.
"Goody's been in the outfield plenty of times,'' Gardenhire said. "Guys are just trying to do too much.''
Murphy followed each of his two home runs with cartwheels in the dugout, something he has never done and doesn't plan on doing again.
"This place has the biggest dugouts I've ever seen, and I said there was space to do a cartwheel,'' he said. "Then I said if I hit a homer, I was going to do one. I was rounding third when I realized I actually had to do it, and then I had to do one the second time.''
Murphy does cartwheels with his daughter, who wasn't impressed.
"My wife texted me to say that my daughter said they were the worst cartwheels she had ever seen. She's kind of a perfectionist.''
BOYD'S HOMER ISSUES
Boyd has given up seven homers in his past two starts, giving him 19 in 11 starts at Comerica Park. Justin Verlander has the stadium record with 20 in 2016.
The teams play the second game of a three-game series on Wednesday evening, with Detroit's Edwin Jackson (2-5, 9.35) making his second start since returning to the Tigers. Marco Gonzales (12-9, 4.25) is scheduled to pitch for Seattle.
ESPN Stats & Information and The Associated Press contributed to this report.
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