The Olangapo-born 26-year-old stopped the clock at 10.25 sec, sweeping aside defending champion Jirapong who finished fifth.
Indonesia claimed the silver and gold medals, with Yaspi Boby and Iswandi both clocking 10.45. Boby edged his compatriot in his reaction time out of the starting blocks.
“I just tried to get out as good as possible…I don’t think I had the best start. But I am just happy with the win,” Cray said after the race.
The Filipino-American in May became the first Philippine athlete to qualify for the 2016 Rio Olympics, meeting the qualifying mark of 49.40 sec for the men’s 400 metres hurdles at the Cayman Invitational Athletics.
Earlier, his fellow Filipino-American Caleb Stuart smashed the SEA Games hammer record by more than three metres (10 feet) to win gold at the start of the athletics competition in the biennial SEA Games, being held in Singapore for the first time in 22 years. – Agence France-Presse