Ben Brust scored 19 points and No. 4 Wisconsin remained unbeaten with a 75-71 victory over No. 22 Iowa on Sunday night.
Wisconsin (15-0, 2-0 Big Ten) matched the best start in school history, tying the 1911-12 and 1913-14 teams.
The game was physical at times, drawing loud protests from both coaches.
But Iowa coach Fran McCaffery boiled over after a foul was called on Gabriel Olaseni that sent Nigel Hayes to the line.
McCaffery was ejected with 12 minutes to play after two technical fouls were called. He continued to confront the officials as his assistants tried to restrain him.
Brust then hit all four free throws off the technical fouls, and Hayes converted one of two on the personal.
That turned a 41-39 Iowa lead into 44-41 Wisconsin advantage.
Hayes then scored on a drive to cap off a 12-2 run.
Iowa would not go away.
After Hayes missed a wild shot, Roy Marble, who led Iowa (12-3, 1-1) with 27 points, collected the outlet pass and drilled a 3 to pull the Hawkeyes within 64-63 with just less than 3 minutes to go.
He grabbed a miss by Brust, got the ball back later in the possession and drained a 3 to put Wisconsin up 67-63.
Aaron White failed to convert on a layup on Iowa's next possession, and both teams traded missed 3s before Dekker converted a three-point play off a fast break.
That pushed Wisconsin's lead to 70-63 with 1:07 left, and Wisconsin held off Iowa's final flurry.
Josh Gasser added 14 points for Wisconsin.
Iowa was in command for much of the first half as Wisconsin struggled to find its shooting touch.
The Hawkeyes were dominant on the glass, turning 11 offensive rebounds into 18 second-chance points.
Wisconsin, meanwhile, grabbed nine offensive rebounds but only got one point out of them.
The Badgers fell behind 19-9 by missing 12 of their first 13 shots from the field and three of six free throws.
Wisconsin responded with a 13-4 run to pull within a point. But Iowa again went on a run to lead 35-24 at halftime.