No. 12 Wisconsin survived its first test in life without Russell Wilson, but received a scare from Northern Iowa en route to a 26-21 win.
Danny O'Brien, a transfer from Maryland who took over for Wilson, had a strong debut, completing 19-of-23 passes for 219 yards and two touchdowns.
"For a first-time quarterback, those numbers were very impressive," Wisconsin head coach Bret Bielema said. "He made some great decisions."
Like Wilson, who transferred from North Carolina State, O'Brien is eligible to play this season due to the graduate student exception rule.
Montee Ball, a 2011 Heisman Trophy finalist who was recently assaulted by five men on campus, ran for 120 yards on 32 carries and scored a touchdown for the 21st straight game.
Northern Iowa, which reached the quarterfinals of the FCS playoffs last season and only lost by a point at Iowa State, was also starting a new quarterback.
Freshman Sawyer Kollmorgen started slow, but finished 18-for-34 with 265 yards and three touchdowns, leading the Panthers to 21 second-half points and a chance to take the lead in the fourth quarter.
"The factor of them starting to stay with the play longer from offensive line to receivers, and Sawyer starting to make the throws, I think everything started to come together," Northern Iowa head coach Mark Farley said.
Northern Iowa receiver David Johnson caught two of the touchdowns and picked up 107 yards in the loss.
Northern Iowa was unable to cross midfield until midway through the third quarter, when it was trailing by 19.
The Panthers worked their way inside the Wisconsin 40 when they faced a 4th-and-4. Kollmonger found Brett LeMaster in the seam for a 21-yard completion and later lofted a 2-yard touchdown to Chad Owens in the back of the end zone to make the score 19-7.
Wisconsin responded on the following drive early. O'Brien faked a hand off and found Jared Abbrederis open down the field for a 53-yard touchdown.
Northern Iowa quickly responded. Kollmorgen hit Johnson open on the right side. Johnson fended off numerous tacklers and broke free for a 55-yard touchdown.
Northern Iowa forced a punt then went back to work. Kollmorgen converted a 4th-and-7 inside Wisconsin territory then found a wide open Johnson for a 31-yard touchdown on the next play to come within five with 7:24 remaining.
The Panthers forced a three-and-out and took over at their own 25 with just over five minutes left.
Kollmorgen picked up first downs facing 3rd-and-10 and 2nd-and-15, but was unable to convert a 4th-and-4 with 2:46 remaining. Kollmorgen's pass was tipped at the line by Wisconsin defensive lineman Ethan Hemer and it fell incomplete.
Ball and Wisconsin ran out the remaining time and held on for the win.
On the game's opening drive, Wisconsin reached Northern Iowa's 15-yard line, but was forced to settle for a field goal.
After settling for a 35-yard field goal in the second quarter, the Badgers finally found the end zone.
After completing a 22-yard pass on 3rd-and-22, O'Brien hit Abbrederis in the back, left corner of the end zone with 54 seconds left in the half to open up a 13-0 lead at half.
Wisconsin scored on their first drive of the second half. On a 61-yard scoring drive, Ball picked up 29 yards on the drive including a 1-yard touchdown plunge. After the extra point was blocked, Wisconsin led 19-0.
Wisconsin has won 33 straight non-conference games ... Wilmot Wellington and Garrett Scott each had 15 tackles for Northern Iowa ... Neither team turned the ball over ... Wisconsin is 11-0 against FCS opponents ... In Northern Iowa's last game against a ranked opponent, the Panthers lost 17-16 against No. 22 Iowa in 2009.