CLEVELAND — Lane Thomas hit a three-run homer in a five-run outburst before Detroit got an out, and the Cleveland Guardians unleashed their lights-out bullpen to complete a four-hitter in a 7-0 win over the Tigers in an AL Division Series opener on Saturday.

Thomas’ shot — on his first career postseason swing — helped the Guardians cool off the Tigers, who stormed into the playoffs with a second-half surge before sweeping AL West champion Houston in the wild-card round.

“It started with the guys in front of me,” Thomas said.

Tanner Bibee pitched 4 2/3 innings before Guardians manager Stephen Vogt swung the door open to baseball’s best bullpen to finish off the Tigers. Relievers combined for 4 1/3 hitless innings to finish and match the largest shutout victory margin in Cleveland postseason history.

Detroit struck 13 out times and didn’t get a runner past first in the final four innings.

Cleveland’s bullpen was as advertised. Rookie Cade Smith (1-0) replaced Bibee and struck out all four batters. Tim Herrin took care of the seventh, Hunter Gaddis the eighth, and Emmanuel Clase, who led the AL with 47 saves, worked the ninth.

“It’s incredible. to come out and do what they do, day in and day out, especially during the season, 162 (games), it shows what we have back there,” Thomas said.

David Fry added a two-run, sixth-inning double for the AL Central champion Guardians, who were unaffected by not playing for almost a week with a first-round bye.

Game 2 is Monday, when the Tigers will turn to Tarik Skubal, the favorite to win the AL Cy Young Award, to try and even the best-of-five series.

The 2,327th meeting between Detroit and Cleveland was the first between the franchises and Central division rivals in the postseason.

It was as good as over after one inning.

Tigers manager A.J. Hinch has made the right decisions for months as his young club went from being under .500 at the trade deadline to qualifying for the postseason with a 33-13 flourish since Aug. 11. Hinch used his bullpen in Game 1 from the start and it backfired.

The Guardians sent nine batters to the plate in the first with Thomas’ moon shot into the left-field bleachers opening the 5-0 lead. Cleveland became the first team in AL postseason history to score five runs before recording an out. Steven Kwan got it rolling with a leadoff double against Tigers starter Tyler Holton (0-1) and Fry walked. José Ramírez followed with a hard hopper to third that Zach McKinstry misplayed for an error, allowing Kwan to score. Josh Naylor’s RBI single made it 2-0 and Hinch pulled Holton after just four batters to bring in Reese Olson — the move blew up in seconds.

Thomas, who batted just .143 with 33 strikeouts in his first month with Cleveland after being acquired from Washington in July, made his first postseason at-bat with the Guardians unforgettable.

He turned on Olson’s first pitch — a slider down the heart of the plate — and launched it over the wall, sending the majority of 33,548 fans inside Progressive Field into a frenzy.