Jim Knowles, Ohio State’s defensive coordinator, expects a tough test from Notre Dame running back Audric Estime on Saturday.

“It’s the running back combined with the offensive line,” Knowles told reporters on Tuesday. “The offensive line is talented. The tackles are excellent, and he’s a strong running back.”

The Buckeyes (3-0) allow 121.1 yards rushing per game and 3.5 yards per carry. None of previous OSU opponents produce on the ground like Estime does.

“So when you have an offensive line that works well together and they’re physical and they push at the point of attack, he’s a guy who can get behind that,” Knowles said. “Strong runner but also elusive. He can also make the cuts, so I think it’s a real challenge for us to play behind our pads and play downhill because you’re going to have to put your face in the fan.”

Estime has 521 yards rushing and 5 touchdowns on 63 carries for 8.3 yards per attempt. He’s also a threat in the passing game out of the backfield with 5 catches for 55 yards, 11 yards per attempt, this fall.

As Knowles mentioned, the Fighting Irish have strength at tackle to help Estime take off. Left tackle Joe Alt is a top-tier NFL Draft prospect and right tackle Blake Fisher could also play on Sundays.