Carter had eight rebounds, while Pruitt finished with 13 points. Rich McBride scored 15, hitting 5-of-11 3-pointers. The Illini (18-8, 6-5 Big Ten) went on a 12-0 run early in the second half on the way to their third straight victory.
Tim Doyle scored 16 for Northwestern (11-12, 1-9), which suffered its ninth loss in 10 games and saw its flickering postseason hopes take another hit. The Wildcats would love to reach the NIT -- the tournament Illinois is trying to avoid.
Two years after reaching the championship game, the Illini are in danger of missing the NCAA for the first time since 1999. But they played like a tournament team Wednesday night, outrebounding the Wildcats 40-16. Illinois was 9-for-22 on 3-pointers, while Northwestern hit 3 of 18.
The Wildcats were within 33-28 after Doyle's layup about five minutes into the second half, before Illinois scored 12 straight. Warren started the run with a layup and 3-pointer from the corner and finished it with a basket that made it 45-28 with 10:38 left in the game. McBride added a 3 and Calvin Brock a jumper during the run.
The Illini have been inconsistent in conference play, but with five games left in the regular season, they're finished with Big Ten leader Ohio State and Wisconsin.
Early on, the Illini made it look easy against a team that can give opponents fits with its unorthodox zone defense and Princeton-style offense. Illinois scored the first nine points and were ahead 17-3 and 26-12 before the Wildcats woke up.
Kevin Coble started an 11-point run for Northwestern with a jumper and 3-pointer and hit another jumper that made it a three-point game with 1:38 left in the half.
Pruitt then hit two free throws, and McBride added a 3 from the top of the key with 32 seconds left to make it 31-23.