Paul came off the bench to score 17 of his points in the first half for Illinois (14-5, 4-2 Big Ten), which rebounded from a pair of tough losses on the road with a key conference victory on its home court.
The Spartans (12-6, 4-2) stayed close throughout but couldn't overcome their anemic 39.3 percent shooting from the floor.
Kalin Lucas led Michigan State with 15 points while Durrell Summers added 13.
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