JEJU (South Korea) (AFP) - World No. 4 Justin Thomas brushed off a shaky start to fire a superb nine-under 63 and take a three-shot lead after the first round of the CJ Cup on Thursday (Oct 19).

PGA Championship winner Thomas is three strokes clear of five players on six-under 66 - Malaysia's Gavin Green, the American trio of Chez Reavie, Scott Brown and Patrick Reed, and Australia's Marc Leishman.

Thomas came up short in his bid for a hat-trick of wins at the CIMB Classic in Malaysia last week, finishing in a tie for 17th, and he bounced back from an early wobble at the Nine Bridges course in the first United States PGA Tour event ever to be played in South Korea.

He dropped a shot "really badly" on his opening hole, the 10th, but got it back with interest by eagling the par-five 12th.

That was the start of a run of eight under par for seven holes comprising four birdies and another eagle at the 18th to reach the turn in a scintillating seven-under 29.

"It was a weird day," said 23-year-old FedExCup champion, who has been in sizzling form since winning his first Major in August and was recently voted PGA Tour player of the Year for 2017.

"It started off with a really badly played bogey and then I went on a seven-hole stretch where I kind of went unconscious and that was was pretty much most of my round."

Thomas holed a bunker shot at the 15th for the second of four birdies in a row and chipped in from off the fringe at the 16th for another.

"That's kind of how my day was. Hit two really bad wedge shots and got away with them to steal two bogeys," he admitted.

His second nine was almost boring by comparison featuring three birdies and another bogey at the seventh to finish at nine under par.