Lewis hit four 3-pointers and finished 7 of 9 from the field. Bryn Forbes scored 15 points and Anton Grady added 12 for Cleveland State (18-9, 9-3 Horizon League), which is one game back of Green Bay for the top spot in the standings.
Jake Wiegand and Marc Brown each scored to open the second half and pull Illinois-Chicago within one, 30-29. Grady answered, scoring six points during a 13-3 run to stretch Cleveland State's lead to 43-32 with 14: 59 to play, and the Vikings led by double digits the rest of the way.
Hayden Humes scored 13 points, and Kelsey Barlow added 12 to lead Illinois-Chicago (5-20, 0-11).