Emily Sisson is headed to her first Games nearly 16 months after missing a spot on the U.S. Olympic marathon team.

The 10,000m runner-up from 2019 USAs clinched a berth Saturday at the Track and Field Trials in Eugene, Oregon, with a dominating victory in which she took down a 17-year-old meet record in mid-80 degree heat.

Sisson led all but four of the race's 25 laps to finish in 31:03.82, negative-splitting her last seven 400s from 75.07 down to a 69.26 close and winning by about 70 meters.

"It was hot, but we knew that it was gonna be hot," she said after the race. "I talked to [coach Jerry Schumacher] beforehand and he said let's play to your strengths. The plan was to go out running 76s, 77s … [and] the first 5K try to go through at 15:50 and then try to pick it up."

The Wisconsin-born Nebraska native's time removed nearly six seconds from the previous Trials record of 31:09.65, set in 2004 by that year's Olympic marathon bronze medalist Deena Kastor.

Sisson was trailed in second by this year's Trials 5000m runner-up Karissa Schweizer (31:16.52), who now has the opportunity to attempt the 5K-10K distance double in Tokyo.

The last U.S. women to accomplish the feat were Shalane Flanagan and NBC Sports' Kara Goucher. The duo finished top-nine in both events, with Flanagan earning silver in the 10,000m.

In third was Alicia Monson (31:18.55), a four-time All-American at Wisconsin. Like both Sissons and Schweizer, she'll make her Olympic debut in Tokyo.

American record-holder Molly Huddle, Sisson's training partner, scratched from the race prior to competition.

"I was thinking of [Huddle] this morning and I often watch race videos of 5Ks and 10Ks," Sisson said. "I kinda just like looking at them, I'm a very visual person. I've watched videos of her running and running away from the field."

In February 2020, Sisson entered the U.S. Olympic marathon trials in Atlanta with the No. 5 bib. But she didn't finish, exiting after 21 miles in with less than 16% of the race remaining.

"The Olympic marathon trials, that broke my heart, that was so hard to go through," Sisson said after Saturday's race. "I don't feel like I have a chip on my shoulder or need to prove myself because of that. I always kinda look forward and work hard for whatever the next thing is – had a lot of help with my husband. This is the fittest I’ve ever been."

Just about a year prior she had run the fastest marathon debut by an American woman (2:23:08) on a record-eligible course at the 2019 London Marathon. Jordan Hassay ran 2:23:00 in her debut at Boston in 2017.

"I actually went through a pretty rough patch. I came out of that race pretty broken. I was pretty confused after," she said. "Usually I'm pretty good at moving on after bad races but that one was really hard for me."

That result was Sisson's third attempt before Saturday's 10K at making the U.S. Olympic team — she was 12th in the 5K at 2012 Trials and 10th in the 10K at 2016 Trials.

"[In] 2012 I was a sophomore in college, no expectations," she said. "[In] 2016, I went into the Trials pretty out of shape and I actually overheated.

"This was definitely different. The goal is to win and make the team – some days it works out, and some days it doesn't. I know everyone on that start line went into it knowing they worked really hard."

Sisson's 2019 U.S. 10K title brought her to Doha, Qatar, for the 2019 World Championships where she finished 10th. She placed ninth in the race at the 2017 World Championships in London.

Competition is expected to be fierce in Tokyo. The 29-year-old and her two American compatriots will face Letesenbet Gidey and Sifan Hassan, who both separately broke the event's world record just earlier this month.