Saensak Muangsurin

Boonsong Mansri, known professionally as Saensak Muangsurin, was a Thai professional Muay Thai fighter and boxer. He was a Lumpinee Stadium super-lightweight champion in Muay Thai, as well as a WBC super-lightweight world champion in boxing. In 1975, he won a major world boxing title in his third professional fight, 241 days after his debut, which is still the record over 50 years later. He is also Thailand's heaviest world boxing champion to date. Nicknamed the "World Collapsing Southpaw," he is often regarded as one of the most fearsome punchers in Muay Thai history.