Drew Crawford, a fifth-year senior, scored a season-high 30 points, JerShon Cobb added all 10 of his points in the second half and the Wildcats upset the 13th-ranked Badgers 65-56 on Wednesday night.
Northwestern first-year coach Chris Collins earned his first big win on the road, and the Wildcats got their first victory in Madison since 1996.
Ben Brust's 21 points led Wisconsin, which lost for the fourth time in five games.