KANSAS CITY, Missouri -- One thing is undeniably true about the recent and continued influx of talented young players in the National Women's Soccer League: they would not be in the league right now without Olivia Moultrie.

Moultrie is 18 years old, but is playing in her fourth NWSL season for the Portland Thorns. Her decision to sue the NWSL in 2021 for her right to sign a contract at 15 was the catalyst for the league's current youth movement, an era in which most clubs now have full-team players under the age of 18 -- with several of them already stars.

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"I guess it is cool now, just the amount of signings that are happening because of that," Moultrie told ESPN. "Obviously that wasn't the intent going into it, but of course it's pretty cool to see the game grow that way because that was the intent the whole time: that [if] you're good enough, you're old enough.

"There shouldn't be some number that's stopping you from going toward [your goal]."

Moultrie made international headlines in 2019 when, at age 13, she decided to forego her college eligibility -- she had committed to the University of North Carolina two years earlier -- to turn "professional" by signing a contract with Nike (before the NIL era). Moultrie and her family uprooted their lives in southern California to move to Portland, there was a catch: she had nowhere to play professionally, yet.

FIFA laws restricted Moultrie from playing abroad at her age, while the NWSL's opaque rules ostensibly required all players at the time to be at least 18 years old. Moultrie challenged the NWSL's claim as an antitrust violation, and the parties settled outside of court within about two months in 2021 after Moultrie won a preliminary injunction. Since then, the NWSL has gradually overhauled its Byzantine rules around players under 18, first allowing only specific exceptions before creating an entry mechanism last year that officially allowed teams to sign two players under age 18. That permissible number of under-18 players on each team doubled to four in 2024.

Today, the NWSL is increasingly full of bright young stars, which is important for the league and the United States women's national team as each strives to keep up with the evolving global game. Exceptional teenage players have competed on senior teams for years in Europe, to give one example, and the payoff of that was clear for Spain last year in its 2023 World Cup triumph.

Leading the charge is San Diego Wave FC attacking sensation Jaedyn Shaw, who scored in each of her first three professional games at age 17 in 2022. Her ability to turn pro -- which at the time was still through an ad-hoc mechanism the league made up as individual situations arose -- gave Shaw the necessary experience to already be a focal point for the U.S. women's national team. Shaw recently set a USWNT record by scoring in each of her first five starts.

The examples are numerous: 18-year-old Claire Hutton has started all four games at defensive midfield for the league-leading Kansas City Current, and she has earned the praises of her coach, former USWNT coach Vlatko Andonovski. There is Alyssa Thompson, the No. 1 draft pick to Angel City FC in 2023 as an 18-year-old, and her sister, Gisele, who signed with Angel City before her 18th birthday last year.

Moultrie names Shaw and Thompson as friends from their days together on youth national teams. Moultrie's record as youngest NWSL signing was broken twice in a month last year -- Chloe Ricketts to the Washington Spirit; and Melanie Barcenas to San Diego Wave FC -- and while she doesn't know those players personally, Moultrie recognizes the importance of the NWSL's new standard.

None of those signings could happen without her legal fight. The NWSL might have changed the rules eventually, but there was no hurry to do so. Moultrie's case challenged rules that some legal experts felt could compromise the very integrity of the NWSL's single-entity model.

David Copeland-Smith, who has trained USWNT stars including Alex Morgan and Mallory Swanson through his Beast Mode Soccer business, said Moultrie deserves more credit for being a "trailblazer" in the space. Copeland-Smith started training Moultrie at age 11 after USWNT great Mia Hamm sang Moultrie's praises. To him, it was clear even at age 11 that Moultrie was more than just a talented player.

"The biggest thing with Olivia is that we haven't even scratched the surface of her potential," Copeland-Smith said. "Because she is a player who just wants to improve all the time. And she was like that when she was young; she always wanted exercises that were going to push her. She didn't just want to go through it. She wanted something that's going to test her. And I think, being in the NWSL, that was definitely done, because all of a sudden you're playing against full-grown women and competitors. They don't care if you're 16, they're going to kick the s--t out of you."

A 13-year-old had never been in the NWSL space before. "It was uncomfortable for everyone when I first got here," Moultrie said. It was unclear what the plan was, too, since she could not sign a contract. For the first two years, Moultrie trained with the Thorns' senior team while playing for the academy teams.

In some ways, Moultrie sounds like a typical teenager: the thing that she wanted -- to turn pro -- couldn't come fast enough.

"Once I was in the situation I was like, dang this is taking forever," Moultrie said. "Obviously, anyone who was on the outside looking in was probably like: 'oh my gosh, this is moving at lightning speed.'"

When Moultrie speaks, however, she elicits the confidence and wisdom of a player who has now been around a professional environment for five years, not a typical 18-year-old. She describes herself as a "Type-A checklist" person who sometimes needs to be reminded that she should just enjoy the moment.

"She is wise and mature beyond her years, so professional," Thorns and USWNT teammate Sam Coffey said. "I just have no doubt that she'd going to continue to take those positive steps forward and learn at this level and learn at the club level ... It's rare to see a young player that mature and that hungry to just continue to be their best, and I think when you combine the two, it's a scary combination."

This season, Moultrie is a clear focal point of the Thorns' midfield, a role she earned last year with 11 starts and 21 appearances. Recent call-ups to the USWNT for the Concacaf W Gold Cup and the SheBelieves Cup further validated how much her game progressed over the past year. She scored twice in her USWNT debut in February, a 5-0 win over the Dominican Republic.

As Moultrie self-critiques her game, she talks about being "more efficient" as an attacking midfielder, and references Kevin De Bruyne, Lionel Messi and Andres Iniesta as players she models her game after. She is excited to raise the expectations for herself and to accept more responsibility, and isn't afraid to state how big her goals are.

"I think, at the end of the day, the whole process is someday I want to be considered the best player in the world," Moultrie said. "That's what I'm striving for, so all of these things along the way ... how do you tangibly define that? I think there's a lot of ways to define that, but that's what I want my career to reflect, so that's kind of what I'm chasing every day. That means winning with my team, putting together great performances consistently, playing for the national team, winning trophies."

This is the progression of a player with three full seasons already under her belt. Had Moultrie never challenged the NWSL's old system, she would have just played her first four games as a professional. Instead, she accelerated not only her path to stardom (by her timelines, perhaps it has been too slow), but the opportunities for other young players, too.

"I'm living, literally, my dream," Moultrie said. "This is exactly what I want. I'm a professional and I get to go after my goals every day."

That's all anybody who's good enough and old enough ever wanted, too.