“If you blinked, you missed it.”

That’s what one of the “American Ninja Warrior” announcers said when Kai Beckstrand breezed through a challenging obstacle course that tested everything from balance to upper body strength during the Season 15 premiere.

The 17-year-old from St. George, Utah, was so fast that he finished the course in a little over 54 seconds — more than 20 seconds ahead of the second-fastest time of the night.

And if there were any viewers who thought that was a fluke, Beckstrand’s appearance during the semifinals Monday night should put all doubts to rest: He flew through the semifinal course in under a minute — again beating the second-fastest time of the night by more than 20 seconds.

“For real?” Beckstrand exclaimed after he hit the buzzer and the announcers told him his time. “I knew I was moving, but not that quick.” 

A No. 1 seed on “ANW,” Beckstrand has now secured his spot in the finals. The teenager previously competed in the finals when he made his “ANW” debut in Season 13, ultimately getting eliminated partway through.

Beckstrand has returned to the show this season stronger and faster — “He has been flawless,” one of the announcers said during this semifinal run.

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But the Utah teen has at least one really tough competitor he’s got to beat if he’s going to successfully make it through the finals and claim the $1 million prize — something that’s only been done twice in show history.

Kai Beckstrand competes against Kaden Lebsack

Beckstrand is fast, but 17-year-old Kaden Lebsack has been the “Last Ninja Standing” two seasons in a row now. While “American Ninja Warrior” only awards the $1 million prize to the contestant who is able to complete all four stages of the finals in a certain time frame — again, something that has only been done twice — the show does award the contestant who makes it the farthest (and if there’s more than one, the fastest) a $100,000 prize.

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And for Seasons 13 and 14, that prize has gone to Lebsack. Both years, Lebsack timed out on the last stage of the nationals — a 75-foot rope climb that must be completed within 30 seconds.

Now, Lebsack — who had the second-fastest run of the night behind Beckstrand, completing his semifinal run in a little over 1 minute and 18 seconds —  is looking to go one step farther this season and claim the $1 million prize. But that feat is also well in reach for Beckstrand, who announcers have said is a favorite to win.

The teens met a few years ago and raced against each other on Season 2 of “American Ninja Warrior Jr.” (Lebsack won that race).

In a real treat for viewers, the teens ended up competing against each other once again during the semifinals Monday night. As the two top contenders this season, the ninjas were competing for a safety pass in the national finals — which would allow a do-over should a contestant splash down at any point during the obstacle course.

What transpired was an unbelievably fast neck-and-neck race. It was impossible to predict until it was over: With Beckstrand right behind him, Lebsack completed the course in just under 38 seconds to hit the buzzer and claim the safety pass, which will give him a second chance should he need it in Las Vegas for the finals.

“They were moving so fast it looked like they barely touched the obstacles!” the announcers exclaimed. “That was a main event for the ages right there!”

How other Utah competitors did in the ‘American Ninja Warrior’ semifinals

Monday night’s semifinal round saw five other Utah competitors.

Mady Howard, a nurse and former Southern Utah University gymnast, won her match against fellow Utahn Ally Tippetts Wootton and secured her spot in the national finals (she had the fourth-fastest time among the female competitors).

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She started watching ‘American Ninja Warrior’ when she was 7. Now, this Utah teen is on it

“I think that ‘Ninja Warrior’ is a great outlet for me,” Howard previously told the Deseret News. “It’s my fun outlet where I can play like a little kid on a playground, where I can go and be competitive and kind of chase my own dreams. It challenges me to be a better person and a better mom. I seriously just love it.”

Beckstrand and Howard were the only Utahns to make it through to the finals. Beckstrand’s father, “ANW” veteran Brian Beckstrand, and rookies Violet Kepo’o and Josh Ferguson were eliminated during the semifinals.

Anna McArthur, a 16-year-old from St. George, will compete in the semifinals next Monday.

Note: The semifinals continue Monday night at 7 p.m. MDT on NBC. The national finals begin Aug. 21.