The defense caught its breath and came up with one more big play.
Jonathan Taylor ran for two touchdowns to help the offense overcome a sluggish start and the Badgers swarmed Northwestern before holding on for a 33-24 win on Saturday.
"We knew it was going to be a hard one," Wisconsin coach Paul Chryst said. "There (are) a lot of lessons to be learned in this one."
Alex Hornibrook threw for 197 yards and a touchdown, settling down after two interceptions on deep balls in the first half. Garrett Dooley had three of Wisconsin's eight sacks.
Wisconsin (4-0, 1-0 Big Ten) stood up the Wildcats (2-2, 0-1) late to seal the win in each team's conference opener.
The Badgers led 31-10 with 9:54 to go on safety Natrell Jamerson's 36-yard interception return for a touchdown.
It looked good for Wisconsin then since its defense hadn't allowed any second-half points all season.
But Northwestern finally got its offense going, scoring two quick touchdowns to close the gap to 31-24. Wisconsin then went three-and-out, but Anthony Lotti's perfect pooch punt was downed by Jamerson at the 2.
Two plays later, quarterback Clayton Thorson couldn't find a receiver out of his own end zone and was sacked by D'Cota Dixon for a safety with 58 seconds left.
"I was a little shocked," Dixon said about how long Thorson held on to the ball.
The mobile Thorson was outside the pocket, where he can do damage. Unfortunately, he was working from his own end zone.
"There (are) no ifs, ands or buts about it," Thorson said. "I've got to throw it away."
Northwestern's fourth-quarter flurry overshadowed what was an otherwise dominating day for Wisconsin's defense.
Jamerson finished with two interceptions. The front seven applied withering pressure most of the afternoon. Northwestern running back Justin Jackson was held to 25 yards on nine carries.