Rory McIlroy is two shots off the lead after the second round of the Kolon Korea Open at the Woo Jeong Hills Country Club course near Cheonan.
The world number six shot a 69 that could have been even better had he not bogeyed the ninth, his last.
The four players ahead of the Northern Irishman are all South Korean, with Hong Soon-sang carding a bogey-free three-under-par 68 to top the leaderboard.
He is on five under overall, one stroke ahead of compatriots Kang Sung-hoon, Kim Hyung-tae and Hwang In-choon, while tied fifth with McIlroy are two more home favourites - Yu Gyoung-yoon and first-round leader Jang Ik-jae.
McIlroy, who is playing his first tournament after a month-long break, had a topsy-turvy opening nine, with two birdies and a bogey coming in his first four holes. He then carded three bogeys in a row from 14 to 16.
However, the former world number one bounced back to score five birdies in the next 10 holes.