NEW DELHI, Oct 21, 2012 (AFP) - Thaworn, playing one flight in front of Ramsay, birdied the last hole in regulation play when his seven-iron approach shot landed about one foot from the hole as he closed with a five-under-par 66.
Ramsay, the overnight leader, needed a par putt on the last for victory but made a three-putt bogey for a 68 as the pair returned to the par four 18th hole at the Karnataka Golf Association course.
The Scot then blasted his tee shot into a creek and was penalised. His third shot landed in the back of the green and he chipped to about 10 feet past the hole as he two-putted for double bogey.
Thaworn, who won the Hero Indian Open in 2005, made a two-putt bogey for victory after hitting his second shot into the greenside bunker. His win pushed him to the top of the Asian Tour Order of Merit.
"To be honest, I didn't expect to win with the way I was driving the ball this week," he said, according to a statement from the tournament organisers.
"It means a lot that I've won a second Hero Indian Open title and that I'm now leading the Asian Tour Order of Merit."
The Thai finished with a 14-under-par 270 and won $198,125.
Thaworn, who was two shots off the lead at the start of the day, struggled with his driver but rallied with acute iron play and a sharp short game in a round of six birdies against one bogey.
"I think I only found two fairways in regulation and I didn't see where Richie was on the 18th hole until the crowd started shouting. It was a huge surprise to me but I'm glad I won," he said.
Ramsay rued an unlucky break in the play-off as his remarkable third shot, which he hit over the trees, landed in a pitch mark just after the green.
Rising Thai star Panuphol Pittayarat bogeyed the last hole to finish one shot from the play-off. Shiv Kapur was the best Indian golfer as he shot a 66 for fourth place on 272.
Anirban Lahiri of India, a two-time Asian Tour winner, Arnond Vongvanij of Thailand and Jaakko Makitalo of Finland were a further two shots back in fifth place.
Leading final scores:
270 - Thaworn Wiratchant (THA) 69-68-67-66, Richie RAMSAY (SCO) 66-66-70-68
271 - Panuphol Pittayarat (THA) 67-68-69-67
272 - Shiv Kapur (IND) 67-71-68-66
274 - Anirban Lahiri (IND) 70-71-66-67, Arnond Vongvanij (THA) 71-67-67-69, Jaakko Makitalo (FIN) 67-68-68-71. 2
275 - Peter Hanson (SWE) 70-71-68-66, Chiragh Kumar (IND) 69-71-67-68