Phachara, born on May 3, 1999, stunned an experienced field that included a number of the country's leading golfers, to win the $65,000 (£43,000) Singha Hua Hin Open by four shots on Sunday and etch his name in golf's record books.
With the victory, Phachara replaces New Zealand sensation Lydia Ko, who won the 2012 New South Wales Open three months prior to her 15th birthday, as the youngest winner of a professional golf event.
"I am really, really happy to win against so many top players," Phachara, who had to qualify for the tournament, said in a statement from the organisers.
"My putting was the key and I also worked very hard with my caddie. We planned everything carefully."
However, Phachara's joy will be short-lived as the daily grind of school life looms large on his horizon.
"Tomorrow (Monday) is a public holiday and the first thing I need to do is call my friends and catch up on homework," he added after his four-under-par final round 67 took him to 13-under for the tournament.
Fellow Thai Prom Meesawat, who finished tied for second with Sutijet Kooratanapisan, was simply stunned by the teenager's performance.
"It is amazing to see a kid play like that. I had a bogey-free round but look at what he did!" Prom said.
- Sports & Recreation