The Orioles have spent most of September limping into the postseason. Their most likely first-round opponent is sprinting in.

Baltimore spent the past two weekends playing mostly close games against a surging Detroit team. The Tigers went from a trade deadline seller to a September Cinderella, and now they’re a legitimate postseason contender in an American League lacking elite teams.

When the Orioles traveled to the Motor City on Sept. 13, the Tigers were a cute story but one that would likely end with them coming up just short of a playoff spot. After two series wins over Baltimore and sweeps of the Kansas City Royals and Tampa Bay Rays, Detroit has the inside lane to occupy the AL’s second wild-card spot and travel to the top wild-card team in the first round of the postseason.

That team? Baltimore.

If the Orioles want to win their first playoff series since 2014 — in fact, their first game — they might have to go through the Tigers. Six weeks ago, that sentence would’ve been laughable. Now it’s a bit worrying.

While it matters far more how the Orioles play in the postseason than who their opponent is, the Tigers are not a great matchup for Baltimore. At the very least, if the Orioles could choose, they’d likely prefer to play the Minnesota Twins (and maybe even the flailing Royals) than Detroit in the best-of-three AL wild-card series.

The Tigers, winners of five straight, are perhaps the hottest team in baseball, and they’ve been one of the majors’ best in the second half. Inexplicably, they traded away starting pitcher Jack Flaherty and two other big leaguers at the deadline and then went 33-17 since. The Tigers’ odds to make the postseason went from 0.2% in mid-August to 7% before they nearly no-hit the Orioles in their first matchup against each other to above 90% after completing their sweep of the Rays on Thursday.

“It’s a really good pitching staff,” manager Brandon Hyde said. “They have a great bullpen, they have a bunch of really good arms. … They’re really athletic, they’re young, they’re playing loose. They played really good defense this series, also. Made a bunch of really good plays against us.”

Before taking the first two games versus the Yankees this week in New York, the Orioles hadn’t played well against any team in September — excluding the sub-MLB-caliber Chicago White Sox — and won exactly one game in five straight series. The Tigers, meanwhile, have played well seemingly every night and have won six straight series.

They were 3 1/2 games back of a playoff spot and eight games back of the Orioles on Sept. 13. Facing the Orioles six times in a 10-day stretch should’ve been a speed bump for the Tigers’ playoff push. Instead, it was one for Baltimore’s hopes of catching the Yankees in the AL East.

Detroit has its fair share of solid ballplayers — ace Tarik Skubal, left fielder Riley Greene, slugger Kerry Carpenter and a stout bullpen — but it’s far from a star-studded roster. There’s no Gunnar Henderson on that team, and the Orioles’ core is more talented.

But behind manager A.J. Hinch, who led the Houston Astros to the 2017 World Series title, the Tigers are playing with house money — unburdened by the pressure and with nothing to lose. Shortstop Trey Sweeney made a reckless and dangerous diving catch in the ninth inning of Saturday’s stunning victory that Baltimore let slip from its grasp. Sunday, they nabbed Colton Cowser trying to advance to third because of third baseman Jace Jung’s hustle and pitcher Ty Madden’s smarts to cover the bag. Then, Parker Meadows robbed a home run from Cowser that could have decided the game.

Those high-effort, heady plays are ones that good teams make, and they can make the difference in postseason games just like they did against the Orioles this weekend.

What might also be an advantage for Detroit in a playoff series is the Orioles have yet to see left-hander Tarik Skubal. The AL Cy Young Award front-runner has a 17-4 record with a 2.48 ERA and 221 strikeouts. The Orioles have struggled against left-handed starting pitchers with a 10-16 record since the beginning of June, although the return of Jordan Westburg and Ramón Urías could help that. Facing Skubal for the first time of the season in Game 1 of a playoff series would be a slight advantage for the Tigers.

Even worse, the Tigers have now seen Orioles ace Corbin Burnes twice. Burnes dominated Detroit both times, so perhaps he has the Tigers’ number, but doing so a third time against the same team in three weeks is no easy task.

None of this is to say the Orioles can’t beat the Tigers. They’d likely be favored by oddsmakers and projections systems. Baltimore, by almost all metrics, is the better team.

But October baseball is just as much about momentum — a force so strong it either doesn’t exist or sabermetrics can’t quantify it — as anything else. The 2023 Orioles ran into a buzzsaw in the Texas Rangers, and the Tigers could pose a similar threat.