Dosunmu suffered the injury in Tuesday's loss to Michigan State. He was fouled hard by Spartans freshman Mady Sissoko late in the game; Sissoko was ejected after being hit with a flagrant 2 foul. Dosunmu didn't leave the game, however.
Brad Underwood didn't offer a specific timeline for Dosunmu's return, but said he wouldn't play against Nebraska on Thursday night.
"Ayo is eager to play," Underwood said. "We are hopeful for his return to our lineup."
Dosunmu is a Wooden Award candidate, averaging 21.0 points, 6.3 rebounds and 5.3 assists. The 6-foot-5 guard is No. 35 in ESPN's NBA draft rankings.
Illinois, No. 5 in this week's AP poll, saw its seven-game winning streak snapped against Michigan State on Tuesday. The Fighting Illini are 16-6 overall, 12-4 in the Big Ten.