Chun In-gee coasted with an eight-under 64 on Thursday, to take a five-stroke lead after the opening round of the Women's PGA Championship.
Scoring a bogey on the opening hole of the Blue Course at the Congressional Country Club in Maryland, the world number 33 quickly responded with four birdies over the rest of the front nine.
Birdieing the par-five 11th, Chun then closed the round out with four consecutive birdies to post a 64 for the day, putting her ahead of compatriot Choi Hye-jin, who finished Thursday with three-under 69.
In an otherwise challenging day in wet conditions on the Blue Course, following heavy rain overnight, the world's top three players finished some way off as Chun blitzed the field.
Ko Jin-young ended Thursday with an even score of 72, while world number two and defending champion Nelly Korda finished on one-under.
After taking out the U.S. Women's Open earlier in the month, Minjee Lee had a tough day out, posting three bogeys to eventually finish on one-over.