SINGAPORE - The true measure of a champion is the one who remains cool and calm under pressure.

The ever-smiling Nitithorn Thippong, who lives just off Bangkok, is such a personality.

That is why the composed Thai worked his way into being the deserving winner of the Asian Tour's US$1.5 million (S$2.1 million) International Series Singapore on Sunday (Aug 14) at Tanah Merah Country Club's Tampines course.

In sensational fashion, the boyish-looking 25-year-old carved out a three-under 69 for a 16-under 272 total to edge out Malaysia's Gavin Green (71), fellow-Thai Phachara Khongwatmai (71) and Canada's Richard Lee (67) by one shot.

On a moving day of high drama - oftentimes with at least eight players within two shots of the lead - steady Nitithorn enjoyed the championship feeling even before the real thing happened.

Having finished his round with a fabulous putt from 20 feet on the last hole to save par and keep a share the lead, he watched from the clubhouse as the last flight was in business.

And when co-leader then, Taiwanese Chan Shih-chang hit a poor drive into water and Gavin Green, one shot behind, sent his errant tee-shot into what seemed trouble, hordes of fans declared the Thai as champion and took photographs with him.

After much deliberation with the officials, Chan had to go back to the tee-box for his third shot and Green, who was fortunate to find his ball on terrible rough, had to chip on to the fairway.

At the break, the affable Nitithorn obliged the fans freely with a warm smile, but kept declaring to them that "I am not champion yet. Anything can happen."

Suddenly more drama erupted as the siren went for stop of play because of lightning. And when play resumed after 40 minutes, his main rivals could not garner the winning feeling.

Out-of-contention Chan played a double-bogey, Phachara's birdie was not enough and Green just missed a 15-foot putt for birdie that would have forced a play-off.

Nitithorn, whose 68 on Saturday included two eagles, considered this triumph as the biggest in his nine-year pro career and won US$270,000.

After the presentation ceremony, Nitithorn said: "I was truly focused on the process. I made some great putts, kept the ball mostly in play, and must thank my caddie for the saving-par on the par-five 18th .

"I hit a wayward drive to the right rough between trees, chipped out and found the green in four. Facing a difficult putt, I read it as left-right. But my trustworthy caddie Thirdeong Pratbepthong said 'slight left'. That proved to be the winning putt in the end."

Pre-tournament favourite Patrick Reed, who is part of the breakaway LIV Golf Invitational Series, shot a 67 to finish on tied-31st on 280, and he aced the par-three 14th.

The world No. 46, who won the 2018 US Masters, said: "A lot of up and downs. It was weird, one of those days when I did not hit the ball well. Had a shorty on 13 which I missed, then I go ahead and make a hole-in-one.

"I was actually between eight-iron and nine on 14, we had 171 yards. I was trying to figure out the wind. Decided on a soft eight, and it never left the flagstick.

"That's my third in tournaments, and the biggest one right here as it kind of got the momentum going because it was really rough early on, needed to spark the round."

Australian Todd Sinnott remembered the day for his lowest round of 64 that moved him 28 spots to joint-fifth with Chan to win US$55,500 each.

Final results (selected)

• 272 Nitithorn Thippong (Tha) 68 67 68 69
• 273 Richard T. Lee (Can) 70 69 67 67, Gavin Green (Mas) 65 65 72 71, Phachara Khongwatmai (Tha) 67 66 69 71
• 274 Todd Sinnott (Aus) 68 70 72 64, Chan Shih-chang (Tpe) 69 68 66 71
• 276 Jarin Todd (USA) 74 67 68 67, Ryo Hisatsune (Jpn) 70 69 68 69, Ryosuke Kinoshita (Jpn) 70 70 67 69, Jaco Ahlers (Rsa) 70 66 69 71, Peter Uihlein (USA) 68 70 67 71
• 280 James Leow* (Sgp) 74 67 71 68, Patrick Reed (USA) 73 68 72 67
• 283 Hiroshi Tai* (Sgp) 72 69 69 73
• 285 Scott Vincent (Zim) 64 73 71 77
• 286 Mardan Mamat (Sgp) 72 71 71 72

* Amateur