The Illini (14-5, 4-3 Big Ten) led 53-43 on a 3-pointer by Paul with 13:08 to play. But they had to hold off a late Spartans charge and ultimately won with seven free throws from four players that built a two-point lead back up to 65-57 with 5:25 left.
Michigan State (12-6, 4-2) was led byKalin Lucas, who scored 15 points.Draymond Greenhad 12 but fouled out with 36 seconds to play.
The Illini led 41-37 at halftime and outscored Michigan State 12-6 over the first 7 minutes of the second half.
They closed that stretch with two inside points from Richmond on a long pass from McCamey that sliced just over the outstretched hands of two Spartans defenders and a 3-pointer from Paul after Richmond forced a Michigan State turnover.
After a dunk that had revved up the home crowd, Lucas hit a 3-pointer that quieted fans and pulled the Spartans to 59-53 with 10:28 remaining.
Just 46 seconds later,Delvon Roesank a short basket that cut the Illini lead to 59-55. With 8:55 to play, Roe tipped in a miss to it to 59-57.
The Illini, after riding their outside shooting much of the night, spent the next 3 minutes methodically rebuilding their lead at the free throw line.
Mike Tisdalehit one, followed by two each from McCamey, Mike Davis and Richmond to stretch Illinois' edge back to 65-57.
Davis finished with 11 points and 11 rebounds.
Paul's first-half outburst included nine points on 3-for-3 shooting from 3-point range.
The sophomore guard, coming off the bench, hit one 3 that capped a 7-0 Illini run that gave Illinois a 28-23 lead with 8:24 to play in the first half.
Just under 5 minutes later he nailed his last 3-pointer of the half from the baseline in front of the Michigan State bench, giving the Illini a 38-31 cushion. Less than a minute later he added a three-point play when he was fouled byKeith Appling.
Paul played defense, too.
With 2:16 to play in the half and Illinois leading 41-35 he sprinted the distance of the court to chase downKorie Lucious, cleanly swatting down what looked like an easy layup off an Illini turnover.
After losing their shooting touch in back-to-back road losses to Penn State and Wisconsin, Illinois found its form. The Illini went 25 of 47 (53.2 percent) from the field and made eight of their 17 3-pointers.
Illinois hit 61.5 percent of its shots - including six of its nine 3s - in the first half and led by as many as eight over the first 20 minutes.
Richmond missed some practice time before the Wisconsin game and didn't play to deal with unspecified family issues. He issued a statement denying rumors that he was considering transferring.
Roe had eight points and 10 rebounds for Michigan State.