A little rest went a long way.
"I've been building up confidence throughout the season," Nunn said.
Groce said the Illini had very little physical practice the past two days, and he noticed a big difference at the end of a difficult stretch of 10 road dates in 14 games.
"We rolled the dice a little bit, but I thought our guys played tonight, I mean they really did," he said.
Northwestern (10-7, 1-3) shot 46 percent, compared to 42 percent for Illinois, and also enjoyed a 35-30 rebounding advantage. But the Wildcats still dropped their third consecutive game.
Illinois turned Northwestern's 11 turnovers into 14 points, and the Wildcats did not score off the Illini's three turnovers.
"For us, I didn't like our activity defensively," Northwestern coach Chris Collins said. "I thought we were in the right spots, but we have to be a lot more active. We need to be getting some more deflections."
"I wasn't as aggressive the past couple games and I wanted to change that," Olah said. "From now on, I need to be as aggressive -- or more aggressive -- than I was today."
Nunn had a hand in two of the game's flashiest plays on consecutive Illinois possessions in the second half. The Chicago native fed Nnanna Egwu for a big dunk, and then showed off his athleticism when he slammed home an alley-oop from Jaylon Tate for a 43-35 lead with 16:58 remaining.
Nunn's fourth 3-pointer made it 60-50 with 6:16 left, but the Illini were unable to put the Wildcats away. Jershon Cobb made two foul shots with 29 seconds left to get Northwestern within three.
The Illini then called timeout and just managed to get the ball in to Cosby, who was short on the front end of a one-and-one. Tre Demps' spinning layup trimmed Illinois' lead to 66-65 with 12.2 seconds remaining, but Nunn made two free throws to make it a three-point game once again.
"That's habits, practicing free throws. At the end of the game that was clutch," Nunn said. After McIntosh made two foul shots for Northwestern, Illinois threw the ball ahead to Nunn, who made two more free throws to make it 70-67 with 1.2 to go. The Wildcats then turned the ball over on the ensuing inbounds pass and Hill closed it out with two more foul shots.
Cosby was 7 for 15 from the field, including a 4-for-8 performance from 3-point range. The junior transfer from Seton Hall had just 23 points on 7-for-33 shooting in his previous four games.
"The coaches and my teammates know what I'm capable of and I do, too," Cosby said. "I stayed confident through it all. I kind of worked on it. Tonight they fell."
Illinois: Egwu blocked a shot in the first half to run his career total to 174, putting the 6-foot-11 senior in a tie with Derek Holcomb for third on the school list. The Illini record is 177 by Deon Thomas from 1991-94. ... The Illini went 12 for 14 at the line.
Northwestern: It was Olah's first double-double since he had 17 points and 10 rebounds in a 101-49 victory over Mississippi Valley State on Dec. 14. The 7-foot junior has four double-doubles for the season.