Seoul: In-form Rattanon Wannasrichan of Thailand grabbed the first round lead at the Maekyung Open after a sparkling six-under-par 65 yesterday.
Rattanon carded an eagle, five birdies and a solitary bogey for a one-stroke advantage over highly rated countryman Phachara Khongwatmai and South Korea's Hur In-Hoi.
Yoon Jung-Ho, Kim Tae-Hoon, Lee Chang-Woo, Park Il-Hwan and amateur Jang Seung-Bo, all from South Korea, shot matching 67s for joint fourth place, two shots off the lead, at the undulating Nam Seoul Country Club yesterday.
"My driving and putting were good today," said the 21-year-old Rattanon, who finished 27th in last year's OneAsia Order of Merit. "I put myself in good position with my driver today which made it easier to get close to [some] tough pins.
"This is my third time playing the Maekyung Open and I am determined to do well this year after missing the cut in 2016."
Rattanon, who finished fourth in last week's Yeangder Heritage in Taiwan, went on a 10-hole scoring blitz from the fifth with five birdies and an eagle at the par-five 14th to sneak ahead of Hur (66) in the morning session.
Starting at the 10th, the South Korean -- a winner on the Japan Tour in 2014 -- had five birdies to reach the turn in 30. He picked up another shot at the first hole before dropping his only stroke of the day on the seventh.
Phachara, who turned 18 on Wednesday, handed himself a belated birthday present by collecting six birdies and dropping just one shot for a 66 in afternoon play.
He has been making headlines since becoming the youngest winner of a professional tournament when he took the Singha Hua Hin Open on the Asean PGA Tour in July 2013, aged 14.
His biggest achievement to date came at February's ISPS Handa World Super 6 Perth when he finished runner-up to Australia's Brett Rumford in the hybrid strokeplay and match play event. He was joint 18th at last week's China Open.
Defending champion Park Sang-Hyun and 2016 runner-up Lee Soo-Min were cruising up the leaderboard before faltering on the back nine.
Park carded a double bogey at the 13th before recovering with two birdies for a 68, while Lee had a triple bogey seven at the 16th when sitting at four under for his round. He birdied the 17th and parred the last for a 69.
Cho Rak, who won the 2017 OneAsia Qualifying School and finished joint 24th in China last week, continued his good form with a fine 69.
The 36th edition of the Maekyung Open is the second tournament on the 2017 OneAsia schedule after the China Open.