You've never seen cage-fights like this!
Children as young as four take part in the much criticized mixed martial arts.
Inside the cage at a gym in Winchester, Tennessee, we found extraordinary scenes of boys fighting boys, girls fighting girls, and even girls fighting boys.
You'd be surprised at how many moms are in the audience.
"I know the referee is trained to stop it before it gets to the point where they're hurt," said one mom.
Another mom said, "it's hard to see your kid. You want them to win, but you don't want to see them get hurt."
Supporters of mixed martial arts say the adult version is "the fastest-growing sport in the world."
One of the top three movies this past weekend was the mixed martial arts film Warrior, starring Tom Hardy and Nick Nolte.
But the sport's violence has provoked controversy across the nation. It's actually illegal in New York and Connecticut.
Former presidential candidate John McCain famously called events like this one "human cockfighting."
"I don't think he's probably ever been to one," said Christie Hawkersmith, the wife of the gym's owner.
She says there are strict safety precautions for kids in mixed martial arts bouts.
"Under 18, they cannot punch to the face, it's not an all-out brawl. They learn skills and they try to master those skills," said Christie.
Christie's husband says the kids learn discipline and self-esteem.
He says people who think mixed martial arts are too violent for youngsters are ill informed.
"It's a proven fact that football has more injuries, and more severe injuries, than [mixed martial arts] by far," said owner Bunny Hawkersmith.
Four-year-old twins Danika and Nyomi Arellano were both competing the day INSIDE EDITION was at the gym.
When the girls are not in the cage at Bunny's gym, they like to take part in a more ladylike pursuit: beauty pageants.
It's a split decision on which type of event they prefer.
"Pageant," said Danika.
"MMA," said Nyomi.
And what's their mother's view of the controversial sport?
"Deep inside yeah, it's like, Uhhh!"
Rita admits she has mixed emothions when she sees her daughters fight.