NORTH LIBERTY — Iowa City Liberty has earned its Dome debut.

In just its seventh season as a varsity football program, Liberty advanced to the state semifinals for the first time after dispatching traditional playoff heavyweight Ankeny, 21-13, in a Class 5A state quarterfinal game Friday night at Liberty High School.

“I couldn’t be more proud of our team,” first-year Liberty Coach Scott Chandler said. “Our defense was kind of maligned early in the season and those guys just kept their nose to the grindstone, kept getting better week by week by week and they showed up tonight. … What a performance by them.”

Liberty (10-1) will play Southeast Polk (7-4) in a 5A state semifinal Friday at 7 p.m. at the UNI-Dome in Cedar Falls.

In the first four games of the regular season, Liberty allowed over 37 points per game on defense. In its two playoff wins over Waukee and Ankeny, the Lightning have surrendered just 13.5.

Fittingly, it was a Liberty defender who sealed the game. With the Lightning clinging to a 14-7 lead, senior defensive back Dallas Miller stepped in front of an Ankeny receiver at the sideline, intercepted a pass and returned it 43 yards for a touchdown with 1:58 to go.

“I knew they were going to run that play, they ran it all game,” Miller said. “I know that receiver is just going to stop like that and I just took it away from him.”

Miller also had a hand in Liberty’s 14-7 halftime advantage when — on fourth down and goal to go — he took an inside handoff from quarterback Reece Rettig, sprinted along the line and then pitched to trailing tailback Sutton Koller for a 4-yard touchdown.

“It doesn’t work in practice, but it worked that time,” Miller said. “I’m just happy we scored.”

With the score tied at 7-7 and less than two minutes until halftime, the Liberty offense stayed on the field for a fourth down and 19 yards to go at the Ankeny 27-yard line. Rettig dropped back to pass and heaved the ball into the end zone, where Collin Decker made a competitive play for the go-ahead touchdown.

“Just a ton of adrenaline,” Decker said. “It was surreal, honestly. But I am just glad I came down with it and was able to secure it for that score.”

Decker led Liberty with six receptions for 43 yards, while senior tailback Owen Drapeaux ran for 90.

Ankeny (6-5) was denied a fourth state semifinal berth in five years.

“We have just got so much to prove still,” Decker said. “We haven’t won anything yet. Everybody was underestimating us at the beginning of the season. … There were rankings where we were last in our district. We just look at that every day and go back to work.”