Indiana State closed the first half on a 19-5 run to take charge and pulled away in the second period to slow down Creighton's would-be march to the Missouri Valley Conference title.
Creighton now leads Indiana State and Wichita State by a game at the top of the league race.
The Sycamores (15-8, 8-4 MVC) hit half their field goal attempts and turned the ball over just five times. R.J. Mahurin added 17 points for Indiana State and Manny Arop had 13.
Creighton (20-4, 9-3) was led by Will Artino with 13 points. The Bluejays had won three in a row after dropping two straight.