BURIRAM, Thailand (Reuters) - Loud cheers erupt as two boys trade punches at a boxing ring in Thailand's northeastern province of Buriram.
After dominating five rounds, the winner is declared; 11-year-old Nanthawat Promsod, who is better known by his boxing name - "Super Big Saksandee".
He earned 3,000 baht (S$126) for winning the fight, and earns 1,500 baht for each match-up that he takes part in.
He is one of at least 10 boxers aged 15 or less in the district of Satuk, where nearly every village has a boxing camp.
"Muay Thai", or Thai boxing, is said to be 2,000 years old. Known as "The Art of Eight Limbs", it makes extensive use of elbows, hands, knees and feet.
Thailand's national sport is increasingly popular overseas too but in this Southeast Asian country it can provide a way out of poverty, as those who climb to the top of the sport can earn a lot of money.
The country's rural northeast is home to most star boxers who have gone on to win international recognition, such as welterweight Buakaw Banchamek, a two-time K-1 World MAX champion.
Hailing from Surin province, Buakaw, 35, started fighting when he was eight years old, and won his first international kickboxing tournament in 2004 in Tokyo.
Nanthawat wants to follow in his footsteps.
"I want to become a champion," said Nanthawat, who has had 40 fights over a two-year career and in recent months has won more than 10 consecutive fights.
"I will be proud if I win at least one championship belt."
But as more Thai children, even some preschoolers, flock to Muay Thai, physicians and children's rights bodies warn the sport could cause chronic health problems, such as neurological disorders.
Jiraporn Laothamatas, a neuroradiologist and director of Thailand's Advanced Diagnostic Imaging Center (AIMC), said a five-year study she conducted showed patterns of brain damage and memory loss in young fighters, compared to non-boxing peers.
"There's no safe boxing, because you can see that when even adult boxers get old, they also get Parkinson's disease because of the brain damage caused," Jiraporn said.
More than 10,000 Muay Thai fighters are younger than 15, the Sports Authority of Thailand (SAT) said last year.
But experts say that figure could be 20 times higher because not all child boxers are registered.
Still, some parents and trainers argue that Muay Thai teaches children discipline and is a valuable source of income.
"The money Nanthawat earns from boxing, we save for him," said his father and trainer, Ong-arj Promsod, 36. "Whenever we are short of money, I give him that money as daily allowance for school."