The 37-year-old Thai, supported by hundreds of fans, could have wrapped up the event two shots better if he had not fired one into the bush that earned him a double bogey on the 18th hole.
Tops in Asia in 2003 and 2004, victory had eluded Thongchai since winning in the Carlsberg Malaysian Open in February 2005. Since 2000, the former paratrooper has triumphed in at least one tournament every year. He finished the season at No. 2, just behind Indian Jeev Milkha Singh.
'I feel very happy, I was very lucky this week,' Thongchai said. 'It is good to win in Thailand. I feel great as I tried my best. My driver and putting worked this week. My putting was good coming in and I made everything. I just missed a few putts this week. It was very good.'
Filipino Frankie Minosa, who enjoyed his best season on the Asian circuit this year, followed Thongchai at second with a 10-under-par 278.
The Manila-based golfer, who will turn 47 this month, benefited by a solid performance on the front nine where he birdied at holes four, seven, eight and nine to score a 2-under-par 70.
Last year top player, Thaworn Wiratchant of Thailand, was neck-and-neck with Thongchai through the mid-mark but faltered on the 15th and 16th holes for a bogey and a double bogey. He plummeted to fourth place with an 8-under 280, one shot behind South Korea Charlie Wi who closed at 9-under 279 for the third place.
Singh landed an even par 72 on the final day for a total of 6-under-par 282 to finish at joint sixth along with Thais Prom Meesawat and Chawalit Plaphol, Australian David Bransdon and American Edward Loar.
'My holiday starts now,' said Singh. 'I'm happy. The way I ended up today, I didn't shoot over par. I didn't hit the ball well the whole week. It's been a long season. It's been a dream year.'
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