Rayvonte Rice, leading the league at 19 points a game entering the contest, scored 15 on just seven shots to lead four Illinois players in double figures in front of 15,390 at State Farm Center.
Penn State's D.J. Newbill, the only Big Ten player other than Rice to score 12 or more in every game, saw that streak end when he was ejected with 8:38 to play after a retaliatory push to the back of Illinois freshman Kendrick Nunn's head.
"I didn't see it live," Penn State coach Pat Chambers said, adding that he missed the lone video replay shown in the arena before official Mike Kitts instructed the scorer's bench to show the play no more.
Illinois coach John Groce also refrained from comment on the skirmish other than to say he didn't see it live or on replay.
Newbill, three points behind Rice for the Big Ten scoring lead coming in, scored just seven on 2-of-8 shooting.
Tim Frazier (17.7 ppg), who combines with Newbill to form the nation's top-scoring backcourt, did not fare much better. The 2011-12 all-Big Ten selection missed 8 of 11 shots and scored 10. Frazier had one assist, more than six below his Big Ten-leading average, and one of just three assists on the day for the Nittany Lions.
Penn State shot 29.89 percent for the game (17 of 57).
"I thought our defensive disposition was really strong for 40 minutes," Groce said.
"We were consistent with our rebounding effort as well. I thought our offense got going in the second half."
Illinois, last in the Big Ten in defensive rebounding through 14 games, outrebounded Penn State 44-33 and grabbed 31 of 42 missed Nittany Lions shots. Every Illinois starter had between six and eight boards.
Illinois (13-2, 2-0) remained in a first-place tie in the Big Ten following a pair of home wins. Penn State (9-6, 0-2) has dropped five of eight after a 6-1 start.
Penn State's John Johnson led all scorers with 18. The junior was appearing in just his third game for the Nittany Lions after transferring from Pittsburgh. Johnson made 4-of-6 from 3-point distance while the rest of the Nittany Lions went 1-for-13.
Joseph Bertrand and John Ekey, fifth-year seniors, each scored 11 for Illinois. Tracy Abrams had 12 points, six rebounds and five assists despite a scoreless first half, which closed with Illinois ahead 28-26.
Illinois scored three points on four of its first six second-half possessions to build a 40-28 lead. Penn State got within seven on three occasions, the last just before Newbill's ejection. Illinois scored 9 of the next 12 following the technical and was not threatened.
The only Illini starter not in double figures, center Nnanna Egwu, scored seven with eight rebounds, three blocks and two steals. Freshman Malcolm Hill had his best game in several weeks, scoring eight in 18 minutes.
"It's like in the last two days (of practice), he said 'I've got to play better,' " Groce said of Hill. "He was dynamite in practice. I liked his disposition out there today. I thought he was really, really good."
Penn State, coming off a 16-point second half against Michigan State on Tuesday after a 47-point first half, was scoreless in this one for the first 6:48.
Both teams return to action on Wednesday. Penn State is host to Minnesota and Illinois is at No. 4 Wisconsin.