The Hawkeyes simply got all they could handle from the reigning Mid-American Conference champions but came out on top after trailing most of the way.
They were down 17-12 when Bullock ran untouched around the left end to put them ahead by one. That happened after Iowa downed a punt at the NIU 1, pinning the Huskies against the goal line.
Rather than take a safety, Northern Illinois punted. Iowa took over on the 24 and Bullock ran it in on third down. The 2-point conversation failed, but the defense held its ground, giving Iowa a tense victory at Soldier Field.
Bullock came up big with the Hawkeyes' running back rotation depleted, and quarterback James Vandenberg taking a beating. Vandenberg was sacked six times and threw for 129 yards.
Jordan Lynch threw for just 54 yards in his first start as Northern Illinois' quarterback but ran for 119. That included a 73-yard touchdown run early in the third quarter to give the Huskies a 17-9 lead, after his fumble on the first drive of the half led to a field goal for Iowa.
The Hawkeyes are eyeing a big jump after two frustrating seasons following the 2009 Orange Bowl season. A 15-11 record during that stretch and a pair of 4-4 finishes in the Big Ten simply didn't sit well, and the Hawkeyes are looking for more.
They brought in longtime Texas coordinator Greg Davis to spruce up an offense that had become so predictable by the end of last season, but fans who were hoping to see a little more flash didn't exactly get that.
Instead, the Hawkeyes pounded the ball even though five players expected to compete for carries were not on the field. And they came up short a few too many times when they had shots at the end zone.
Take this sequence early in the second half.
Trailing by four, Iowa took over on the NIU 14 after Joe Gaglione stripped Lynch of the ball on the first drive of the half. But instead of a touchdown to take the lead, the Hawkeyes settled for a field goal by Mike Meyer after they converted a fourth down at the 5 and stalled at the 3.
Worse for Iowa, Aidan Conlon sprung Lynch with a block on the next possession for a 73-yard touchdown run up the right side that bumped Northern Illinois' lead to 17-9. Another threat early in the fourth quarter ended with a field goal for Iowa - a 50-yarder by Meyer after Vandenberg got sacked for 10 yards by Sean Evans with the ball on the 26.