Walter Pitchford added 13 points and Shavon Shields 10 for the Huskers (10-9, 2-5 Big Ten). Nebraska hit a season-high 11 3-pointers, with Petteway making four and Pitchford three. Smith tied a Minnesota record with eight 3s and equaled his career high of 29 points, scored against Stetson when he was playing for Florida International last season. Smith started in place of Andre Hollins, who sprained his left ankle early in Wednesday's game against Wisconsin.
Deandre Mathieu added 13 points for the Gophers (15-6, 4-4).
Minnesota, which trailed by as many as 15 points in the second half and by 10 with 1:20 to play, pulled to 80-78 with 2.7 seconds left on Daquein McNeil's layup. Shields inbounded to Petteway, who was quickly fouled. Petteway made two free throws to secure the win.
Petteway was 10 of 15 from the field and 11 of 14 on free throws, and he and Shields had six rebounds apiece.
The Huskers made 12 of 17 free throws in the last 2 minutes.
The Huskers improved to 9-1 at the new Pinnacle Bank Arena, with their only loss, a one-pointer, to Big Ten-leading Michigan.
The Huskers, who came in shooting 31 percent on 3-pointers in conference games, made 7 of 14 in the first half while getting out to a 35-30 lead.
The Gophers wouldn't have been that close if it weren't for Smith, who matched his season high for 3-pointers with five in the opening 20 minutes. Smith's start helped Minnesota overcome its five turnovers in the first five minutes.
Nebraska fans razzed Minnesota center Elliott Eliason, a Chadron native who took a scholarship offer from Minnesota instead of Nebraska. He drew boos whenever he touched the ball and went to the bench with four fouls with 5:14 to play. He finished with five points and four rebounds.
Nebraska went on a 13-3 run to start the second half to build a 15-point lead. The Gophers missed their first six shots of the half and committed four turnovers before Maurice Walker's short jumper ended their field-goal drought with 14:17 left.
Minnesota cut the deficit to 10 before Petteway beat the shot clock with a 3-pointer. But a pair of 3s by Smith and Oto Osenieks' baseline jumper got the Gophers within 59-53 with 7 minutes to play.
Petteway led another Nebraska surge to break things open, making a 3-pointer and then stuffing an alley-oop dunk off Benny Parker's pass to make it 64-53.