MINNEAPOLIS  — After watching long gain after long gain by Illinois last weekend, Minnesota coach P.J. Fleck knew a change had to be made to his defense.

Each of the first two drives by the Illini ended with a 72-yard touchdown run. By the end of Saturday’s 55-31 loss , the Gophers had allowed 646 yards of offense, including 430 rushing yards, and five touchdowns that covered at least 30 yards. By the end of Sunday, Fleck had fired defensive coordinator Robb Smith.

“There’s a lot of different things, whether it’s schematics, whether it’s the coaching part, whether it’s the personnel part,” Fleck said Tuesday. “It’s a combination of all of that. As you continue to move forward, you either see that you want this to continue to happen and you believe in that, or you make that change.”

Defensive line coach Joe Rossi was elevated to interim defensive coordinator, with Minnesota (4-5, 1-5 Big Ten) preparing to host Purdue (5-4, 4-2) this week. Rossi assumed command of a defense allowing an average of 43.2 points per game in conference play, along with 507.7 yards per game.

The breakdowns against Illinois were just a continuation of a troubling trend. Star safety Antoine Winfield Jr. injured his foot in the Big Ten opener at Maryland, when the Terrapins rushed for 315 yards amid a slew of missed tackles by the Gophers.