Chandler Harnish threw a pair of touchdown passes for Northern Illinois (2-2).
Adam Weber threw for 373 yards and two touchdowns in the disappointing loss for Minnesota (1-3).
Minnesota broke a scoreless tie in the first quarter with a 28-yard field goal by Eric Ellestad. That kick capped a 13-play, 65-yard drive.
Less than three minutes later, Northern Illinois grabbed a 7-3 lead on the strength of a three-yard touchdown run by Spann.
The Huskies pushed their edge to 10-3 with a 21-yard field goal by Michael Cklamovski.
Minnesota tied the game at 10-10 midway through the second quarter on a 20- yard touchdown pass from Weber to Da’Jon McKnight. Just over a minute later, the Gophers gained a 13-10 lead with a 42-yard Ellestad field goal.
Northern Illinois managed to knot the count at 13-13 with a 35-yard Cklamovski field goal with 2:37 left in the opening half. Then, with just three seconds remaining on the clock, Chandler Harnish tossed a 10-yard touchdown pass to Martel Moore, giving the Huskies a 20-13 edge at intermission.
The only points of the third quarter came on a 21-yard Ellestad field goal, slicing the Minnesota deficit to 20-16.
Just over a minute into the fourth quarter, NIU pushed its lead to 27-16 with a two-yard touchdown toss from Harnish to Connor Flahive. Spann then put the game away with a 61-yard touchdown scamper, making the score 34-16 in favor of the visitors.
Minnesota did cut its deficit to 34-23 with 4:18 remaining in the game on a 29-yard touchdown pass from Weber to Marqueis Gray, but the Golphers were held out of the end zone for the remainder of the tilt.
Northern Illinois won the game despite a 470-378 disadvantage in total yardage.