Ames, Iowa Iowa's weakness was exposed in its first game without injured guard Jeff Horner.
Curtis Stinson scored 20 points, Rahshon Clark added 17, and Jiri Hubalek finished with 13 points and eight rebounds to lead Iowa State to a 72-60 victory over No. 12 Iowa on Friday night, the Hawkeyes' second loss to an unranked in-state rival this week.
Iowa State (6-2) has beaten three straight ranked opponents at home, while Iowa (7-3) lost to the Cyclones for the third time in four games.
"Our goal was to go out there and really attack them," said Iowa State's Will Blalock. "This (win) is number one right now."
Horner had started 101 of the last 102 games for Iowa, but is out for up to five weeks after partially tearing the posterior cruciate ligament in his left knee in the Hawkeyes' 67-63 overtime loss to Northern Iowa on Tuesday.
With Horner out of action, Iowa State forced the Hawkeyes' guards into 13 turnovers and limited them to six assists, while its highly touted backcourt duo of Stinson and Will Blalock, who scored 11 and had eight assists, had their way offensively.
"I thought we handled it as well as our guys are capable of handling it right now," Iowa coach Steve Alford said of Horner's injury.
Iowa's perimeter game, an unexpected sore spot through 10 games, also struggled. The Hawkeyes shot 2-for-15 from three-point range.
Iowa State's frontcourt, which has struggled all season, put forth its strongest effort of the season, outscoring the Hawkeyes, 36-20, in the paint while holding Iowa's Greg Brunner to just 11.
"Our young guys are starting to understand how hard it is and how physical it is (in the post)," Iowa State coach Wayne Morgan said.
Former Cyclone Adam Haluska, booed every time he touched the ball, scored a team-high 16 for the Hawkeyes. Erek Hansen matched his career high with 14 points.