CHAMPAIGN, Ill. -- Mike Tisdale's career performance ruined Northwestern's return to the rankings.
The 7-foot-1 center had a career-high 31 points and grabbed 11 rebounds to lead Illinois to an 89-83 overtime victory over the 25th-ranked Wildcats on Wednesday night in the Big Ten opener for both teams.
Tisdale, who has had his share of critics during his career, led the Illini over Northwestern, which was last ranked in January 1969, when the poll was still a Top 20.
"I love it to be honest. Anytime I get a challenge it?s just kind of fun to shut people down," Tisdale said. "My teammates found me when I was open, and I was able to put it in the basket.
"The guards taking some outside shots was big for us, and obviously me and Mike Davis got the post touches we needed."
Davis had 20 points and 17 rebounds -- his conference-leading seventh double-double -- for the Illini (9-4), who beat Northwestern for the 11th straight time.
John Shurna had 27 points, including four 3-pointers, for the Wildcats (10-2).
"We got off to a good start, but from the get-go, we weren't able to contain Tisdale," Northwestern coach Bill Carmody said. "We just didn't have an answer for him the entire evening."
Ranked seventh in the nation averaging 9.55 3-pointers per game, the Wildcats converted a 3 on their first four possessions to take a 12-4 lead. The Wildcats made 16 3-pointers in the game, shooting 24 percent from behind the arc.
Trailing 42-33 at halftime, Illinois crept back into the game by picking apart Northwestern's 1-3-1 zone. A 19-8 run capped by consecutive 3s by freshman Brandon Paul gave Illinois a 56-55 lead.
"To our kids credit, at halftime we could have laid down and let them run over us," Illinois coach Bruce Weber said. "Our goal was to come out and win the first five minutes of the second half."
After exchanging baskets, the Illini extended their lead to six points on a dunk by Tisdale with 3:33 left in regulation. But the Wildcats, led by Drew Crawford's five points in 3 minutes, closed with an 11-5 run to force overtime.
The Illini struggled to defend the perimeter in the first half, allowing the Wildcats to make 11 of 23 3-point attempts.
A second-half defensive adjustment of switching on screens limited Northwesterns open looks from behind the arc which resulted in Illinois allowing only five 3-point field goals after halftime.
"In the first half I think (Illinois) was pretty responsive to some of our little drives, dribble penetration, we got some open looks that way," Carmody said. "In the second half I don't think we were testing them out enough to tell you the truth. I felt we were settling a little bit for 3s it didn't seem we probed the defense enough."
The Wildcats, who host No. 11 Michigan State on Saturday, attempted 84 shots and committed only three turnovers.
The game featured 13 lead changes and six ties.