Kimberly Dietz added 10 points and was the only other player to finish in double figures for Kansas State (16-14), which was held to its second fewest points of the season and was knocked in the tournament's first round for the first time since 2001.
Iowa State (23-7) got 18 points from Nicky Wieben and 12 from Lyndsey Medders to notch its third straight win of the season over the Wildcats.
But it didn't come easy. Both teams struggle from the field during the first half and Iowa State lead by just four at the break.
K-State quickly made up the deficit during the opening five minutes of the second half and tied the game a 26-26 after a 3-pointer and a free throw by Dietz.
Three more ties followed over the next five minutes before Iowa State began to pull away at the eight minute mark. The Cyclones strung together a 17-8 run down the stretch that was keyed by a barrage of 3-pointers and an old fashioned 3-point play by Wieben to go on top 54-43 with 2:26 remaining.
K-State, which was held to its second fewest points of the season on just 27 percent shooting, got as close as nine twice in the final two minutes but could never put together a significant run to get back in the game.
Turnovers and cold shooting had the Wildcats in an 8-1 hole early. K-State didn't connect on its first field goal until over eight minutes in when Lehning finally broke the drought with a slicing layup that ignited a 6-0 mini run by K-State to make it 8-7.
Iowa State scored the next six points and pushed its lead by to seven at 14-7 when the Wildcats ramped up their defense. K-State held the Cyclones to just two free throws over the next six minutes pulled within a point on a layup by Wheeler that cut the deficit to 16-15.
Iowa State again answered and pushed its lead back to seven following two free throws by Amanda Nisleit with 10.6 second left in the half. But the Wildcats again responded as Dietz canned K-State's only trey of the period with four seconds to go to make it 24-20 Cyclones at intermission.