Ohio State has not been an underdog to a Big Ten team in five years. Michigan is poised to end that streak Saturday.

The Wolverines began the week as 4-point home favorites over the Buckeyes at ESPN BET. It’s the first time they’ve been favored over Ohio State since 2018, when the Buckeyes were also 4-point underdogs against Michigan.

That was the last time Ohio State had been an underdog to a Big Ten team, a stretch of 43 games against conference foes. It’s the longest active streak of being favored against one conference in the nation, according to ESPN Stats & Information. The Buckeyes beat Michigan 62-39 in 2018.

Michigan will be without coach Jim Harbaugh when it hosts the Buckeyes on Saturday in Ann Arbor. Harbaugh will be serving the final game of a three-game suspension for the alleged sign-stealing scheme. Oddsmakers have downplayed the impact of Harbaugh’s absence on the sideline in the Wolverines’ past two games, wins over Penn State and Maryland, and say any added motivation caused by the controversy mitigates the loss of their coach.

Ed Salmons, a veteran Las Vegas oddsmaker with the Westgate SuperBook, estimated Harbaugh was worth “one point” to the spread.

“I wouldn’t be surprised to see the line go back up a little,” Salmons said.

Caesars Sportsbook had Michigan listed as a 6.5-point favorite before last week’s games but reopened at -4.5 on Sunday.

“Little bit of money on the Buckeyes so far,” Adam Pullen, assistant director of trading for Caesars Sportsbook, told ESPN on Sunday. “It stands to reason, because Michigan didn’t look so hot [Saturday] against Maryland.”

On Sunday, the line opened as high as Michigan -5 at Circa Sports, a Las Vegas-based sportsbook known to cater to professional bettors. The number dipped to Michigan -3, before settling back at -4 as of Monday morning.

Michigan was a -170 money-line favorite to win the game straight-up, and the over/under total was sitting at 47 at ESPN BET on Monday.

ESPN BET odds are provided by Penn Entertainment.