After winning his opening bout at Rio 2016, Thai boxer Amnat Ruenroeng has revealed a spell in prison played a big part in launching his career.

Ruenroeng beat Igancio Perrin in the first preliminary round of the men's lightweight category on Sunday, the 36-year-old winning on points.

Victory puts the Thai into the second round of the preliminaries - where he will face France's Sofiane Oumiha.

It could have all been different for Ruenroeng after receiving a 15-year prison sentence for robbing a tourist, but the experience worked in his favour.

"I was in jail for one-and-a-half years until the King pardoned me," Ruenroeng said.

"Life in prison changed me a lot.

"You get disciplined and you learn how to tell what's right and what's wrong. I received an education for the first time.

"I had the opportunity to try boxing, football and kickboxing. But most importantly, prison taught me the importance of family and friends. It helped me develop concentration and it gave me a conscience, to think before acting."

Ruenroeng represented the jail in boxing tournaments, and after his release in 2007 he qualified for the Beijing Games, where he finished fifth in the light flyweight division.