The Badgers shot 55.6 percent in the second half, and went to the free-throw line 31 times over those 20 minutes, hitting 19.
Wisconsin shot 35.5 percent from the field in the first half. Illinois made 29.6 percent.
Illinois, though, took the lead 16-14 on a 3-pointer by Richardson with 8:21 left in the first half.
It looked like a sign that the Illini might be about to find something resembling touch. That didn't happen, but the Badgers started clawing their way out of their own shooting funk. They went on a 19-8 run to finish the half ahead, 33-24.
Two of those points came on Brust's layup with 1:33 to play in the half. The basket was initially denied by a shot clock violation but, after Wisconsin's players pointed out that fewer than 20 seconds had actually elapsed on the shot clock. But it took a lengthy discussion by the officials after Illinois' next possession to get it right.
"I looked up at the shot clock and there was 8 seconds (left)," Ryan said. "We're thinking, there's no way, there had to be more time. So we said excuse us, I think you ought to review that, and they did."
The delay, several minutes long, quieted the crowd and, once the points had been put on the scoreboard, agitated Groce.
The Illini coach's frustration boiled over on the half's final possession. Paul was driving for a buzzer-beating layup, but missed and appeared to draw a foul that wasn't called.
Groce, angry, repeatedly shouted at official Mike Sanzere as the teams left the court. Sanzere gave Groce a technical foul.
Brust, shooting the free throws after the teams came back out for the second half, missed both.