Illinois survived an early Indiana onslaught and leads 32-30 at halftime.
The Hoosiers, playing without their second straight game Verdell Jones III, took an early 11-4 lead.
The Illini rallied behind eight points each by Jereme Richmond and Mike Davis.
Christian Watford leads Indiana with 12 points. Jordan Hulls and Will Sheehey both have six.
Jones is out with inflammation in his right knee.