The Illini (2-2 Big Ten, 12-4 overall) shot just 31 percent from the field in the first half, but still led 31-27 at halftime. They improved to 59 percent shooting in the second half.
The closest the Nittany Lions (0-3, 7-5) got in the second half was 49-45 on a basket by Pete Lisicky with 13:13 left. But Illinois outscored Penn State 17-10 over the next six minutes and took a 66-55 lead on a 3-pointer by Matt Heldman.
Heldman finished with four 3-pointers and 21 points. Chris Gandy had 12 points and six rebounds despite getting into foul trouble in the second half.
Lisicky led Penn State with 18 points, and Phil Williams scored 14 and grabbed eight rebounds. The Lions outrebounded Illinois 36-32, but committed 21 turnovers, as compared to the Illini's 14.
In the opening half, the Illini were up by as many as 12 points, 25-13, on a free throw by Gandy.
But Illinois did not score for almost five minutes as Penn State went on a 14-4 run to pull within two, 29-27, on a free throw by Tim McGovern.
Purdue 78, Northwestern 53
Purdue freshman Mike Robinson scored a season-high 21 points at West Lafayette.
Robinson was 7 of 12 from the field and 7 of 10 from the line. He also added six rebounds, two assists and a blocked shot in 32 minutes against Northwestern (0-3, 5-9) .
The Boilermakers (2-1, 7-6) wore uniforms similar to those worn in the 1930s as part of Mackey Arena's ''Throw-Back Day.''
Michigan State 69, Ohio State 66
Michigan State (2-2, 9-3) outscored Ohio State 27-6 from the free-throw line and made 27 of 34 free throws. Ohio State (2-2, 7-6) connected on only six of 15 attempts from the line.
Ohio State has lost its last seven meetings with Michigan State.
Spartan Mateen Cleaves matched his season high of 18 points, with 12 coming on free throws.
Iowa 78, Wisconsin 53
Hawkeye guard Andre Woolridge led his team with 21 points at Iowa City.
Woolridge went 6-for-10 from the floor and 7-for-7 from the free-throw line as the Hawkeyes (13-3) improved to 4-0 in the conference.
The Badgers (1-3, 8-6) led the Big Ten in scoring defense going into the game. Wisconsin had been giving up only 53 points a game while holding opponents to 36 percent shooting. Iowa shot 51 percent on Saturday.