They have won world Muay Thai titles and have shown no fear against the globe's toughest fighters.
Now, Sophie and Emily Curtain are ready to show their wares on rugby league's biggest stage - State of Origin.
The Blair Athol twins, 17, are in a training camp after being selected for the NSW under-18s women's State of Origin side against fierce rival Queensland. The match will be a curtain-raiser to the open women's Origin game at North Sydney Oval this Friday night.
Emily will line-up for NSW at five-eighth while Sophie has been named on the bench. The sisters will be part of history as it is the first time a women's under-18s Origin match has been held.
The pair were picked on the back of good form for the Wests Tigers in the Harvey Norman NSW Women's Premiership competition.
Sophie, who plays hooker or lock, told the Advertiser it was a great honour to be picked for NSW alongside her sister.
"It's huge to have both of us in the team - it makes it so special," she said.
"We have played together for years and our positions work well together. We know how to read other's game."
Sophie said she hoped to make an impression during Friday night's game and "play to my best ability".
"I hope to make my mark and leave what I do on the field in people's minds," she said.
Sophie has played rugby league for 11 years and said she loved the fierce competition that the sport provided.
"It's not for the faint hearted," she said.
Sophie played for two years before Emily decided to join her on the rugby league field.
"I used to watch Sophie play, she inspired me to sign up and play," Emily said.
Emily said she was delighted to be picked for NSW at five-eighth and she hoped to provide leadership against Queensland.
"I enjoy the chance to lead the girls - they rely on me and can play off me," she said.
"It's very exciting, I will try lead the girls up the field and get the win."
Emily said she was proud to see her sister picked in the NSW side as well.
"It's just going to be an awesome experience," she said.
"It would have been great to have one player in the family selected, let alone two."
The twins' dad Matt Curtain said he was proud of his daughters and they deserved the opportunity.
"The girls are very excited to be part of the game, especially playing in Sydney," he said.
"It means their friends and family can watch."
Curtain said 2019 was a big year for his daughters. Sophie and Emily juggle rugby league and Muay Thai commitments as well as being in Year 12 at Eagle Vale High School.
The twins also try to work when possible.
Sophie and Emily have particularly impressed in Muay Thai. The pair both secured gold medals at the International Federation of Muay Thai for Amateurs (IFMA) Youth World Muay Thai Championships last August.
"They work very hard and need to be disciplined," Curtain said.
The under-18s women's State of Origin match will start at 5.45pm this Friday at North Sydney Oval.