LINCOLN, Neb. (AP) -- Iowa State guard Tracy Gahan said she was far more nervous about her second free throw with two seconds left against Nebraska than she was on the first.

The first, which she calmly sank to give the Cyclones (No. 9 ESPN/USA Today; No. 8 AP) a 77-76 lead despite a roaring crowd, was easy, she said. It was the second, which she had to try to miss, that was difficult.

With Nebraska out of timeouts, Gahan successfully clanked her shot off the left side of the rim and the Huskers couldn't get off another shot. The Cyclones held on to sweep the season series for the first time since 1989.

"Actually it was kind of nerve-racking because coach (Bill Fennelly) was like 'Don't make it,' " said Gahan, who finished with 12 points.

Fennelly's 100th victory at Iowa State kept the Cyclones from their first losing streak of the season. Iowa State was coming off a 58-49 loss at Kansas on Saturday.

"It was a great win for us to come back after that loss," Gahan said. "But I don't think it was a have-to win. It's like coach says -- the only game you have to win is the one that can end your season."

Desiree Francis scored 19 points to lead Iowa State (16-3 overall, 7-1 Big 12). Stacy Frese scored 17, going 4-for-6 from 3-point range in the second half, Megan Taylor had 13 points and Gahan pulled down seven rebounds for the Cyclones, who outrebounded Nebraska 41-29.

Gahan drew a foul as Nebraska's Nicole Kubik went for a steal with the game tied 76-76. She made the first of two free throws but missed the second, and Nebraska's Charlie Rogers got the rebound, only to throw away a pass intended for Kubik.

Nebraska coach Paul Sanderford, who was called for a technical in the first half, was still livid over the call after the game.

"I made a coaching mistake. I told our kids with 18 or 20 seconds left to go that the players would decide the basketball game -- that the officials wouldn't be a factor," Sanderford said.

Kubik was called for traveling in the lane on Nebraska's previous possession, giving the Cyclones the ball with 3.7 seconds left to play.

Kubik and Melody Peterson each scored 15 for the Huskers (11-8, 5-3), who lost for the first time in five games. Amanda Went scored 12 and Casey Leonhardt finished with 11.

Iowa State, which used a 24-2 run to pull away in the final 10 minutes of an 89-66 victory over the Huskers on Jan. 15, couldn't run away with this one.

Nebraska, which trailed most of the second half, got within 66-64 on Went's 3-pointer with 5:50 to play. Peterson then stole the inbounds pass and hit a layup to tie it at 66. Peterson added a free throw on the next possession to give Nebraska its first lead of the second half.

The lead changed hands the next seven possessions before Frese tied the score at 76 with a free throw with 18.5 seconds left.

After Iowa State missed two straight from the free-throw line, Nebraska had a chance to win it when Kubik was called for traveling.

Iowa State led 38-37 at halftime on Frese's jump shot in the lane at the buzzer. Nebraska had taken the 37-36 lead, the Huskers' first of the game, on Isha Kelley's 3-pointer with 12 seconds remaining. The end-to-end series capped a physical first half, which featured 23 fouls and 32 free throws and lasted 55 minutes.

Nebraska lost senior guard Brooke Schwartz indefinitely when she took a hand to the eye from Francis while going for a loose ball late in the first half. Schwartz is averaging 13.8 points per game this season.