Justin Thomas grabs three-shot advantage at The CJ Cup in Korea

FedExCup champion Justin Thomas made a fast start to The CJ Cup by grabbing a three-shot lead after the opening round in South Korea.

Thomas fired a nine-under 63 in scoring-friendly conditions at Nine Bridges Golf Club to pull clear of nearest challengers Patrick Reed, Marc Leishman, Scott Brown, Gavin Kyle Green and Chez Reavie.

Beginning on the back nine, Thomas cancelled out a bogey at the 10th by holing a 15-foot eagle at the par-three 12th and following a birdie at the 14th with a hole-out gain from the bunker at the next.

The PGA champion chipped in from just off the 16th green and added a birdie at the par-three 17th, with a close-range eagle at the 18th seeing him reach the turn in 29.

Thomas rolled in from 10 feet at the third and picked up another birdie at the sixth, before bouncing back from three-putting the seventh from the fringe to pick up a shot at the last.

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"It was a weird day," Thomas said. "I started off with a really bad bogey and then I had a seven-hole stretch where I basically went unconscious."

A final-hole eagle saw Marc Leishman join the group sharing second on six under, with Patrick Reed mixing eight birdies with two bogeys and Chez Reavie posting a blemish-free 66.

Gavin Kyle Green and Scott Brown complete the quintet three off the pace, with Tony Finau one of five players on five under and former world No 1 Jason Day a further stroke back.

Ian Poulter birdied his final two holes to card a one-under 71, with Paul Casey and Adam Scott part of the group on level-par.

Watch The CJ Cup throughout the week live on Sky Sports. Live coverage continues on Friday from 3am on Sky Sports Golf.