Jeju - Justin Thomas shot nine-under par in the opening round of the inaugural CJ Cup and said on Sunday it was "bizarre" he won three days later still on the same mark.
Thomas shot a 63 in benign conditions in the first round and made the Nine Bridges course look ridiculously easy.
It could not have been more different over the next three days as the wind whipped ferociously around the slopes of South Korea's tallest mountain Hallasan - the gorgeous setting on Jeju Island for the PGA Tour's first-ever event in the country.
Thomas was astounded that he finished on nine-under par and that it was still good enough to get him into a playoff against Marc Leishman.
"It's bizarre that that happened," he told AFP.
"I never would have guessed it, especially after the first round. But it really was so, so difficult out there, especially the last two days when it was cold and hitting into the wind: your ball just goes nowhere."
Thomas's third-round 70 in brutal winds was the only time after the first round that he broke par again and he reckoned after that round "for a fact, I played better than I did on Thursday".
He said people watching on TV might think players were hitting bad shots and putting poorly. But without being there it was impossible to imagine the degree of difficulty.
"I mean, I hit a seven-iron from 128 yards on one hole today," he said on Sunday.
A big hitter like Thomas could normally launch that around 180 yards.
"The wind is just so strong and with all the trees and it bounces around and swirls a lot," he said.
"The hardest thing was putting. The gusts when it picks up or dies, you just have to time it so perfectly. It was so difficult."
The exhausted 24-year-old cracked a smile after beating Leishman on the second playoff hole in his final event of the autumn swing.
"I am so excited to not do anything from now on," he said, looking forward to a break after a schedule of nine events in the past 11 weeks - the past two in Asia.
"I have officially nothing left in the tank."
Thomas will rise to a career-high number three in the world when the new rankings are published on Monday.
He had already joined Jack Nicklaus, Tiger Woods and Jordan Spieth as the only players to win five times in a season, including a major, before the age of 25 when he won the Dell Technologies Championship before the CJ Cup.
With three wins in his last seven events and six in the last 12 months Thomas has earned his break.