Brandon Paul had 14 points and eight rebounds in No. 10 Illinois' 64-54 victory over Norfolk State.
D.J. Richardson netted 11 points and Tracy Abrams added nine points for the Fighting Illini (11-0), who next play Eastern Kentucky on Sunday.
"I don't think over the course of the 40 minutes our energy, our focus, our effort level was where it's been," Illinois head coach John Groce said.
Rashid Gaston tallied 12 points and eight boards for Norfolk State (6-6), which had its four-game winning streak snapped.
The Spartans defeated Missouri in the second round of the NCAA Tournament as a No. 15 seed a year ago and were able to hang around until the end.
Illinois netted the first seven points of the second stanza and built a 39-29 cushion.
But the resilient Spartans battled back. They responded with the next seven points as Kris Brown nailed a 3-pointer and Gaston made a pair of buckets to cut the deficit to 39-36.
Later, Gaston's layup pulled the visitors within 54-51, but the Illini outscored Norfolk State, 10-3, the rest of the way as Illinois began to hit the offensive glass.
After both teams exchanged turnovers, Richardson's driving layup went down and Pendarvis Williams missed a triple at the other end for the Spartans.
With a little over a minute to play, Illinois took the clock down and Abrams missed a layup, but was able to secure his own rebound. He then missed a pair from the foul line, but Sam McLaurin was able to come down with the board made both his foul shots to make it 58-51 with 51 ticks to play.
The hosts made 6-of-8 from the line down the stretch to secure the win.
"We came in and gave a great effort for about 35 minutes and they took over about the last five minutes," Norfolk State head coach Anthony Evans said.
Norfolk State led, 24-19, with five minutes remaining in the opening half before the Illini countered with an 12-2 run before taking a 32-29 edge into the break.
Illinois pulled down 15 offensive boards and outrebounded Norfolk State, 38-30 ... Both teams shot 26.1 percent (6-of-23) from beyond the arc ... Illinois shot just 35 percent (21-of-60) from the field.