Alysa Liu and her coach Laura Lipetsky react to Liu's score in the women's free skate at the 2019 U.S. Figure Skating Championships on Jan. 24, 2019 in Detroit.

DETROIT -- There were some subtle hints Friday that something special could happen at the U.S. Figure Skating Championships. It began during warm-ups for the final group of women competing in the event, which is part of the 2019 Team USA Champions Series, presented by Xfinity.

Defending U.S. champion Bradie Tennell and newcomer Alysa Liu commanded everybody’s attention. Tennell, who led after the short program, moved with confident power and sophistication. And Liu, a mere 13-year-old who stood in second place in her first senior-level nationals, threw down clean triple axels like they were the easiest thing in the world.

However, things radically changed during the free skate, as Liu rewrote the history books to become the youngest U.S. figure skating champion ever. She finished first with 217.51 points. Tennell fell and finished second at 213.59, while Mariah Bell was third with 212.40 points.

Liu’s stunning display of eight triples, including an unprecedented two axels in one skate by an American female, set a new standard.

“I am kind of out of it right now,” Liu said, with a somewhat blank on her face as she absent-mindedly touched the championship medal hanging around her neck. “It’s not fully sunk in yet, I am not thinking about anything I just did.”

That can be forgiven, given the magnitude of what happened, and her tender age. Liu said still likes to play tag with her friends, ride her bike and play video games with her siblings.

She is a tiny (4-foot-7), young teen who just did a very big, grown-up thing.

The previous-youngest U.S. champion, Tara Lipinski, watched Liu’s skate in person. Lipinski, back in 1997, was only 14 when she won the title. One year later she was the Olympic gold medalist. Now a commentator for NBC, Lipinski was awed by Liu’s poise.

“She just became a teenager and she possesses the technical skill and the drive of a seasoned veteran,” Lipinski said. “Do not forget this name. She’s really going to push the next generation of U.S. skaters.

“She really has it all. She doesn’t just have the technique, she has that fire and ambition and she came here to win. She is a little firecracker.”

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A week before her 21st birthday, Tennell dominated the short program Thursday, with her score of 76.70 setting a U.S. championships women’s record. She had set the previous record in 2018, with she scored 73.79 in introducing herself as the new American skating champion and star to watch.

Up-and-comer Liu, meanwhile, scored 73.89 in the short.

Tennell went third-to-last in Friday night’s free skate, with the pressure of being both the defending champion and the lone Olympian in the field.

Tennell had issues in her Romeo and Juliet-themed free skate, stepping out of her triple lutz-triple loop, and then falling on the front end of her triple lutz-triple loop for a major deduction. She looked disappointed with her skate, worth 136.99.

“That was not my best skate,” said Tennell, who won Olympic team bronze in 2018. “I am disappointed, but there is always something to be learned from skates like this. I am excited to get home, to work harder than ever, and fix the mistakes.”

Liu skated immediately after Tennell, and nailed eight triples — including throwing in an extra triple flip at the end for good measure. When Liu’s gigantic free skate of 143.62 was announced to the crowd at Little Caesars Arena, everybody gasped. Then cheered. Liu dissolved into heaving tears of disbelief and joy.

Because of Liu’s age, she is ineligible to represent the U.S. at the world championships at the junior or senior level right now. She can compete on the junior international level next year. Seniors have to wait until the 2021-22 season. Tennell and Bell are likely to represent the U.S. on the 2019 world championships team.

Liu’s tiny stature became a moment of comedic relief during the medal ceremony. She was standing on the ice, giving congratulatory hugs to her competitors on the medal stand. When it was Liu’s turn to get to the top step, a near 2-foot-high platform, she needed help.

Tennell and Bell nicely — and literally — lent a helping hand to boost her up.

It was the only thing Liu needed help with all day.

Joanne C. Gerstner has covered two Olympic Games and writes regularly for The New York Times and other outlets about sports. She has written for TeamUSA.org since 2009 as a freelance contributor on behalf of Red Line Editorial, Inc.