Justin Thomas made a blistering start to The CJ Cup at Nine Bridges, firing a nine-under 63 to earn a three-shot lead on Thursday.
Thomas, the FedEx Cup and US PGA Championship winner this year, was in fine form in the first round in Jeju, South Korea.
The American bogeyed his first hole – the 10th – but was then red-hot, making eagles at 12 and 18 and four straight birdies from 14 through 17.
Thomas slowed on his second nine, but he finished with a 63 after capitalising on the par-fives at Nine Bridges Golf Club with two eagles and two birdies.
The 24-year-old, who was tied for 17th at the CIMB Classic last week, is three shots clear of the chasing pack.
"It was kind of a weird day," Thomas told the Golf Channel. "It started off with a really, really bad bogey and I had a seven-hole stretch there where I basically kind of went unconscious and that was pretty much most of my round."
Patrick Reed birdied his final hole to move to six under, while Marc Leishman is alongside the American after an eagle at the 18th.
Chez Reavie, Gavin Green and Scott Brown also opened with 66s.
In the first PGA Tour event to be played in South Korea, a group of five players are a further shot back in a share of seventh.
Tony Finau, Charles Howell III, Russell Henley, Jhonattan Vegas and Ollie Schniederjans carded 67s.
World number nine Jason Day finished strongly, with birdies on four of his final seven holes seeing him shoot a four-under 68 to be tied for 12th.
His fellow Australian Adam Scott and England's Paul Casey are further back after even-par 72s.
|Morgan hails ´outstanding´ Buttler century|
|Paine to discuss ODI future after England whitewash|
|Cuper unsure of Egypt future as El Hadary nears milestone|
|Koepka ´shutting down´ until Carnoustie|
|Quintero and James plot Colombia´s way through uncharted territory|
|Federer upbeat despite shock Halle defeat|
|Journalists should round on Vettel - Verrstappen|
|Poland 0 Colombia 3: Falcao´s maiden World Cup goal revitalises Pekerman´s side|
|World Cup 2018: Cossack kids, Swan Lake and the Selecao in Rostov-on-Don|
|Maria takes maiden title in Mallorca|
|Hierro: I am 100 per cent the coach of Spain|
|Busquets recognises Iniesta´s burning ambition|
|Denmark v France: Tolisso hoping for second chance|
|Eight-try Wakefield hammer sorry Widnes|
|World Cup 2018: A panda, a tapir and a nightmare for Willy in Nizhny|
|Senegal´s Wague makes African history in World Cup|
|Cilic fights back to beat Djokovic in enthralling Queen´s final|
|Neymar and Suarez among players to send Messi birthday wishes|
|Strength of Senegal and Japan´s determination could trouble England and Belgium|
|Hamilton questions Vettel punishment after Bottas´ race ´destroyed´|
|Brilliant Buttler seals whitewash in Old Trafford thriller|
|World Cup 2018: An egg-and-spoon race, vodka and the Pogbas in Kazan|
|Queiroz tells his Iran players to follow the ´three Rs´ against Ronaldo and Portugal|
|Pizzi calm over Salah threat|
|Japan 2 Senegal 2: Honda gatecrashes Cisse´s party|
|Harden should be MVP ´hands down´, says World Peace|
|Southgate optimistic over Alli recovery for Belgium decider|
|Neymar´s tears no surprise to Fagner|
|Unhappy Renard continues ref rant|
|Wallace takes BMW International title despite Olesen 61|
|Hamilton cruises back to standings summit with France win|
|In-form Kvitova defends Birmingham title|
|Southgate responds to toughest England week in record-breaking style|
|Uruguay not thinking about Portugal or Spain, insists Cavani|
|Coric stuns Federer to claim title in Halle|
|England 6 Panama 1: Kane hat-trick sees Southgate´s side sail through|
|Australia v Peru: Juric keeping the faith as Socceroos chase unlikely last-16 spot|
|England surpass class of 1966 in Panama rout|
|Nigeria v Argentina: All eyes on Messi to rescue final World Cup chance|
|NSW seal Origin series with comeback win|
|World Cup 2018: Stalin´s bunker, a space museum and Serbian specials in Samara|
|Croatia looking out for number one - Lovren|
|Heritage at back of Australian minds ahead of potential Croatia encounter|
|It may be my last World Cup - ´Realistic´ Pogba determined to reign in Russia|
|Lionel Messi´s birthday: What might the Barcelona star wish for?|
|Russia readying Dzagoev for last-16 clash|
|Germany apologised for reaction aimed at Sweden bench|
|Picture this! Sterling starts for England against Panama|
|World Cup 2018: A Russian romp, Maradona and the party in Moscow|
|Happy birthday, Lionel Messi! 10 of the Argentina star´s best goals|
|Modric worthy of Ballon d´Or, says Lovren|
|Sigurdsson ready for Croatia reunion as Iceland go for broke|
|Iceland v Croatia: Dalic to rest stars for Hallgrimsson divorce hearing|
|Men´s tennis will have to ´wake up´ after Federer and Nadal, says King|
|Tennis star Djokovic backs VAR despite Serbia controversy|
|Socceroos have deserved more at World Cup – Skoko|
|Dodgers top Mets in Kershaw´s return from DL|
|MLS Review: Red Bulls end Dallas´ unbeaten run, Sporting stage comeback|
|Hierro: This Spain team similar to 2010 World Cup champions|
|Dowrich, Holder lead Windies fightback after poor start|
|With Neymar back, Brazil are World Cup favourites – Lugano|
|Alba: I don´t understand the criticism of Messi|
|He has sacrificed a lot – Stuani praises Suarez|
|Manning says Brees deserves to break his record for career passing yards|
|Hornets want Walker to play entire career with Charlotte|
|Avalanche sign Grubauer to three-year extension|
|Argentina struggles down to team, not just Messi – Hierro|
|Casey leads Travelers by four after firing 62|
|Scotland run riot in Argentina as Hourcade tenure ends in defeat|
|Germany´s Rudy in doubt for South Korea clash|