Lee Ki-sang shot an 8-under 64 on Saturday to take a one-shot lead over Anthony Kim after the third round of the $750,000 CJ Invitational.
The South Korean thrilled local fans at the Haesley Nine Bridges Golf Club in Yeoju in a near-perfect round that included a hole-in-one.
That eagle came at the fifth and followed four successive birdies that gave Lee a sensational start. He finished with a 15-under total of 201.
Kim started the day three shots ahead of the chasing pack and his 4-under 68 leaves the Korean-American with a 14-under total of 202.
Tournament host K.J. Choi managed a 5-under 67 to post a 12-under total of 204, three shots behind the leader.
Thailand's Prom Meesawat is on 10-under 206, level with David Oh, another South Korean.