Kayla Harrison overcame sexual abuse to become a world champion judoka and now has her sights set on the PFL lightweight title. (2:48)

COCONUT CREEK, Fla. -- As children ran around the mats and parents settled into their seats at American Top Team's headquarters for a slate of youth classes last week, one noise ricocheted throughout the building: Kayla Harrison's leg kicks. Her sparring session in full swing, the kicks sounded like jackhammers hitting slabs of concrete.

It's easy to see why the two-time Olympic gold medalist in judo is different, why she's the face of the Professional Fighters League's second season and, perhaps, the next superstar in mixed martial arts.

She's the clear favorite of the first women's lightweight division (155 pounds), which kicks off its debut season Thursday at PFL 1 at NYCB Live in Uniondale, New York. If she wins the tournament -- the PFL operates on a regular season and playoff system -- she'll earn $1 million.

"Yeah, a million dollars is great," said Harrison, 28, who won her first three PFL fights last season with three finishes. "But being the best in the world is priceless."

In her attempt to reach the pinnacle of another sport, she's training at ATT and is surrounding herself with some of the best in the world.

Last week, Amanda Nunes, the UFC women's bantamweight and featherweight champion, tied fiancée Nina Ansaroff's hair together midway through an intense sparring session. Jorge Masvidal, the UFC welterweight contender getting ready for a fight against Ben Askren at UFC 239, laughed with "King Mo" Lawal, a popular veteran in the sport. Edson Barboza threw leg kicks nearby. Joanna Jedrzejczyk, the former women's 115-pound champion, bounced around the cage. Pedro Munhoz, who scored a career-altering knockout over Cody Garbrandt in March, hit the heavy bag in the morning and taught a jiu-jitsu class for kids in the afternoon. You get the point.

Just three fights into her career, Harrison has already added her name to the gym's impressive talent pool. She knows she belongs among the elite mixed martial artists and views the PFL as an opportunity to prove as much.

"I have this lifelong background of running around a mat barefoot, throwing people," Harrison said about her impressive judo career. "For me, it's a huge advantage. Some of these girls picked up gloves four years ago and they're like, 'Oh, I want to fight in the cage.' I made my first Olympic trials when I was 14. I won the Olympic trials when I was 18. I won my first gold medal at the world championships when I was 20. I had years of experience, that you can't buy. You can't buy that time."

Two-time Olympic gold medalist Kayla Harrison won her first three professional MMA fights after transitioning from judo, and will now compete for $1 million in the second season of the PFL. Ryan Loco/PFL

Harrison is the headliner for the PFL's 155-pound division, which is essentially the heavyweight division for women. They're bigger and stronger than any other female fighters.

Harrison's sculpted physique stands out at American Top Team. She has defined biceps and sturdy shoulders. Her calf muscles have calf muscles. She said she doesn't cut weight -- although she competed at 170 pounds in judo -- because she doesn't want to feel as if she has to fit a certain profile to compete.

"Women come in all shapes and sizes," Harrison said.

Harrison has embraced the potential of what MMA can mean for her, and what she could mean for MMA. So how did she go from someone who, at one point, felt she might not be cut out for a career inside the cage to the centerpiece of the PFL's second season?

"About a month after I started sparring, I was hooked. I was like 'This is it. This is like judo on steroids.'" Kayla Harrison, on falling in love with MMA

After Harrison's mother took a self-defense course, she figured judo classes might calm her rambunctious 6-year-old daughter. She was right. There was an instant connection for Harrison after she enrolled.

Harrison traveled the world and won junior world titles as a teenager, training with Daniel Doyle, a judo coach in her hometown of Middletown, Ohio. As she soared within the sport, however, she hid a devastating secret.

Doyle, who was in his 30s at the time, sexually abused Harrison from the time she was 13 (August 2003) until she was 16 (April 2007) while she competed in foreign countries, according to a plea agreement.

Harrison, who began training with Doyle when she was 8, said she was groomed to believe she was in a relationship with her coach.

In 2007, she told a friend, and then eventually, she told her mother, who responded by smashing Doyle's car windows with a baseball bat before alerting police.

On Nov. 9, 2007, Doyle pleaded guilty to one count of engaging in illicit sexual conduct in a foreign place. He also confessed to filming one of the sexual acts. He was sentenced to 10 years in prison in 2008.

His actions nearly destroyed Harrison, who lost confidence and questioned herself for years.

"I didn't want to get out of bed," she told ESPN's Allison Glock in a 2017 interview. "I didn't talk to my friends. I cried every day. I slept 12 hours a night. To say that I was at rock bottom is an understatement. I hated judo, I hated my life."

As Kayla's mother noticed the change, she decided in 2007 to relocate to Massachusetts, where Harrison would have the opportunity to train with Jimmy Pedro Jr., a former world champion, and his father James Pedro Sr., who was also a decorated judoka.

Pedro Jr. could see Harrison's potential, but more than anything, he needed patience to build trust with the gifted young woman who arrived at his gym in pieces.

"Devastated, broken, damaged," Pedro Jr. said about Harrison's condition after he first met her. "She did not trust in anybody. She had very, very, very low self-esteem. She was very confused, and quite honestly, she said it many times, she despised life and she despised judo.

"She really put the blame on judo."

As she slowly worked through those feelings toward the sport, and the pain she had suffered through so early in her life, Harrison regained her edge. And she continued to win.

Kayla Harrison won her second Olympic gold medal in judo in 2016, but struggled to come up with a post-Olympic plan until MMA became a part of her life. David Finch/Getty Images

Pedro said he knew that Harrison, who trained with Ronda Rousey as a young judoka, could excel at the highest levels. Harrison overwhelmed every competitor with whom she trained -- often sparring with elite male practitioners because of her "world-class strength," according to Pedro.

"We're talking about a very, very powerful, explosive female athlete," Pedro said. "In her whole judo career, she trained with the best men. She lifted like a professional when she was 15 years old."

Harrison's discipline helped her become the first American to capture a gold medal in judo at the 2012 Olympic Games in London. She won again in 2016 in Rio de Janeiro. She became an ambassador for the sport, gave speeches, and picked up sponsors and a stipend from the United States Judo Association while she competed.

But after winning her second Olympic gold medal and achieving everything she ever set out to do in judo, Harrison was lost. She needed to find a new path -- and a new career.

Initially, mixed martial arts wasn't Harrison's first choice. She didn't like the sport, and while she didn't fear the cage, she thought the fights centered on entertainment value more than merit and ability.

But after hanging around the sport, on the recommendation of the higher-ups with the World Series of Fighting even after she initially turned them down, MMA began to pique Harrison's interest. One day, she decided to spar for the first time, and the competitive edge she had craved since the end of her Olympic run returned.

"It was shortly after the Olympics, I was in a little bit of a depression," she said. "It's like you train your whole life for this one day and then it's over. It's such a high, but then I had no goal. I had no idea who I was when I wasn't Kayla Harrison, the judo player. ... About a month after I started sparring, I was hooked. I was like, 'This is it. This is like judo on steroids.'"

Kayla Harrison defeated Brittney Elkin via submission in her professional MMA debut in June 2018. Ryan Loco/PFL

For two years, Harrison only trained. She toured the country and worked with boxing coaches and MMA experts to help her adapt to the new landscape. She moved fast, picking up tools and concepts at a rate that impressed those around her, and signed with WSOF in October 2016. Harrison later joined ATT, one of the top MMA gyms in the world, in April 2018, and continued to improve at a rapid pace.

"It comes for a reason," her coach, Mike Brown, said of her success. "It comes because of her work ethic. It's the years and years of focus and training. This is just a continuation of that."

WSOF eventually rebranded as the PFL, and as it launched its first season under the new name, Harrison was ready for her first pro fight. During the PFL's first season in 2018, Harrison competed without a division, but fought three times in seven months. In her first PFL fight, against Brittney Elkin, she mounted her opponent before securing an armbar that ended the match. She grounded and pounded Jozette Cotton in her second fight to win by TKO. She threw punches from the top after she took Moriel Charneski's back, and forced the referee to stop the bout in her third fight.

"She's strong," said PFL president Ray Sefo during last week's PFL 1 selection show on ESPN2. "She's so determined to show that she's the best. She wants to be the best."

Harrison accepts the inevitable comparisons to Rousey, her roommate and teammate when they were both young judokas. But she also emphasizes their differences.

"We're two blondes who did judo," Harrison said. "That's about where the comparison ends. She's a very different person from me. I mean, we had the same judo coaches. We were teammates. We were roommates. We lived together. I learned a lot from her both on the judo mat and watching her career in MMA, but we're completely different people and we're completely different fighters."

Yet, as women in the sport, they endure the same scrutiny -- the kind of questions male fighters never face, like whether a fighter is in a prominent spot because of their abilities or because of their appearance. That's why the PFL is bigger than money and status for Harrison.

She has a message to deliver, and the prospect of a championship run in the PFL will help her continue to grow her platform and tell her story.

"I want to be a positive role model for women all over the world," Harrison said.

As she begins to build her name in the world of MMA, as she did in judo, Kayla Harrison's message is clear. "I want to be a positive role model for women all over the world." Jae C. Hong/AP Photo

So what can fans expect when she steps into the cage Thursday night, closing out the PFL's first event of the season?

Harrison says she fights like "the female Khabib [Nurmagomedov]." She's someone who has won at everything she has attempted because she has always refused to expect any other outcome. It's not that losing is not an option for Harrison, it's just that winning is the only possibility she has known since she was a child.

And that's why the entire gym could hear her kicking the pads last week and throwing punches with her gold boxing gloves.

"She's putting people down in the gym with only striking," Brown said. "I think it's with experience, being comfortable and being able to pull the trigger in the fight. But there's no need to challenge yourself. She's an extremely hard hitter. Her punches and kicks are really hard. She has flexible hips so the kicks come up really hard and fast. If you get hit with that, it's gonna be lights out."

Harrison finished last week's training session with treadmill work. Then, she jumped rope. A pool of sweat formed underneath her. The eyes of those in the room that day at ATT were set squarely on Harrison, and one day soon, she's convinced, she'll simply be known as the best.

"My whole goal is to be so good you can't ignore me," she said. "I don't care if you want to watch me because you hate me or you want to watch me because you love me or you want to watch me because you want to see me lose. I just want to be positive and be true to myself in everything that I do. And that includes fighting and how I represent myself outside of the cage."