Northwestern (7-7, 0-1) has dropped two straight after a three-game winning streak.
Wisconsin improved to 14-0 for the first time since the Badgers won each of their 15 games in the 1911-12 and 1913-14 seasons.
No. 8 Wichita St. 82, S. Illinois 67 • At Carbondale, Ill., Fred VanVleet had 17 points, seven assists and two steals and Wichita State remained unbeaten behind 62 percent shooting in its Missouri Valley Conference opener.
Cleanthony Early scored 23 points for the Shockers (14-0, 1-0), the preseason conference favorites coming off a Final Four appearance. The 14-0 start is five wins better than the school's previous best and the 14-game winning streak matches the school mark set in 1953-54 under coach Ralph Miller.
Sean O'Brien and Desmar Jackson had 19 points apiece for Southern Illinois (4-10, 0-1).
No. 24 Gonzaga 73, Saint Mary's 51 • At Spokane, Wash., Przemek Karnowski had 15 points and nine rebounds for Gonzaga against archrival Saint Mary's.
Kevin Pangos added 15 points and eight rebounds for the injury-plagued Bulldogs (13-2, 3-0 West Coast Conference). Starting forward Sam Dower Jr. played sparingly as he continues to recover from a back injury, while Pangos is hampered with turf toe. Starting guard Gary Bell Jr. is out with a broken hand.
Gonzaga has won three straight games since losing to Kansas State. The Zags have won 21 straight WCC games spanning three seasons.
Saint Mary's (10-4, 1-1) played without coach Randy Bennett, who is serving a five-game suspension for NCAA violations.
Thursday's Top 25 basketball scores
• No. 1 Arizona 60, Washington State 25
• No. 4 Wisconsin 76, Northwestern 49
• No. 8 Wichita State 82, Southern Illinois 67
• No. 10 Oregon 70, Utah 68 (OT)
• No. 20 Colorado 64, Oregon State 58
• No. 24 Gonzaga 73, Saint Mary's 51