Traevon Jackson added a game-high 18 points for the Badgers (27-7), who used a 40-6 run that bridged the first and second halves to put away the Patriot League champs.
Sam Dekker added 11 points and six rebounds for Wisconsin, which will face either seven-seeded Oregon or 10th-seeded BYU in the third round of the West Region on Saturday. The Ducks and Cougars battle later on Thursday.
John Schoof and Tony Wroblicky each scored 11 points to lead the overmatched Eagles (20-13), who jumped ahead early but failed to get much going after that.
American lead by seven points, 17-10, when Jesse Reed drained a three-pointer with 9:47 left in the first half, but that was it for the Eagles.
Wisconsin got it going after that and took control heading into halftime. Down 19-13, the Badgers ended the stanza with a 19-3 run. Brust scored eight points during the surge, which gave Wisconsin a 32-22 advantage going into the break.
The Badgers continued to pull away early in the second half. Still leading by 10 points early on, 34-24, the Badgers went on a 19-1 run to put the game well out of reach. Brust scored six points and Dekker added seven points during the burst, which was ended by a Duje Dukan tip-in with 11:03 left for a 53-25 cushion.
The lead later ballooned to 41 points, 69-28, after a Jackson three at the 5:26 mark. Wisconsin cruised to the finish after that.