Davion Warren paced the Red Raiders (10-3, 0-1) with 12 points.
Texas Tech was reduced to just five scholarship players due to health and safety protocols. The Red Raiders were also dealing with injuries to their top two scorers, Terrence Shannon Jr. (14.3 points per game) and Kevin McCullar (13.5 points, 6.1 rebounds).
The Cyclones took control early with an 11-0 run.
Caleb Grill hit consecutive 3s to give Iowa State a 15-4 lead. Tech went 4 1/2 minutes without scoring.
The Cyclones made just one of nine shots during a first-half stretch, but still owned a 30-19 advantage at the break thanks to a late 3 by Kunc.
The offensive struggles continued after halftime. Iowa State went 7:24 without scoring, helping Tech close the margin to 30-26.
Grill ended the drought with two free throws for a 32-26 lead.
Iowa State’s first basket of the second half came when Gabe Kalscheur hit a reverse layup with 10:21 left, making it 34-26.
The Cyclones hit just one of their first 16 shots in the second half.
After winning only two games last season, Iowa State has already beaten three ranked teams this season, including then-No. 25 Xavier and No. 9 Memphis. Texas Tech had won the past five meetings with the Cyclones.
Texas Tech continues a rugged league stretch with a home game Saturday against No. 6 Kansas followed by a trip to No. 1 Baylor on Jan. 11.
Iowa State plays its first Big 12 road game Saturday at Oklahoma.