A night after they scored a dozen runs, the Tigers got nine more -- including Thames' grand slam during a seven-run third -- to win their second straight, 9-4 over Seattle on Wednesday.
"A little bit of everything happened to us tonight," Seattle manager John McLaren said. "We just had a bad ballgame again."
The Tigers, whose offense struggled during a recent road swing, opened their big inning with five straight singles off Jarrod Washburn (2-6) before Thames drove his fifth career slam into the Detroit bullpen in left field.
He doubled in the second and scored Detroit's first run on Brandon Inge's two-out double.
"If you have good at-bats, everything else will be all right," said Thames, who was 2-for-3.
The Tigers managed just 11 runs and went 1-5 during last week's six-game road trip but have 21 runs and 31 hits in two games against the Mariners.
The Mariners are an AL-worst 7-16 on the road.
Kenny Rogers (4-4) allowed four runs in 5 1/3 innings. Richie Sexson and Yuniesky Betancourt hit solo homers for the Mariners.
Ivan Rodriguez, Miguel Cabrera and Carlos Guillen had RBI singles in the Tigers third, setting up Thames' slam. The four RBI were a season high for Thames.
Washburn, who has lost his last seven starts against Detroit, was pulled after giving up 12 hits and all nine runs in 2 1/3 innings. It was his shortest start since Sept. 19, 2006.
"I had good stuff and made good pitches," he said. "With the exception of the one to Thames ... all the pitches they hit were balls.
"They just did a good job of putting the bat on the ball."
Betancourt homered to begin the third and Sexson homered to open the sixth. Rogers gave up a bases-loaded single to Adrian Beltre in the fifth and walked Raul Ibanez to force home another run before ending the threat.
Rogers said he felt great through the first four innings but had a rough fifth after walking three. He didn't like the way he left the game, even after he induced a bases-loaded flyout to end the inning.
"It was a big out," he said, "but getting into that kind of trouble isn't something you want to do."
Tigers relievers Zach Miner and Francisco Cruceta combined to allow just two baserunners after Rogers was pulled.
Detroit got a hit from every man in the starting lineup but managed only two after its big inning.
"Tonight we were very fortunate," Tigers manager Jim Leyland said. "We've had game when teams have done that to us."
Thames' previous slam came last Aug. 10 against Oakland. His four grand slams at home are the most in Comerica Park history. ... The Tigers recalled LHP Dontrelle Willis from a rehab assignment and placed LHP Clay Rapada (biceps tendinitis) on the 15-day disabled list. Willis was available to throw out of the bullpen. Manager Jim Leyland said Willis, who has made just two starts for the Tigers, will eventually return to the rotation. ... Inge played left, center and third at various points of the game. ... Washburn has a 7.38 ERA against Detroit during his losing streak against the club. ... "Home Improvement" sitcom costar Richard Karn threw out the ceremonial first pitch.