Park Sung-hyun made a strong start to the Women's PGA Championship, grabbing a one-shot lead after the opening round Thursday.
The South Korean fired a six-under 66 at Kemper Lakes Golf Club to take the early lead.
Park, the 2017 U.S. Women's Open champion, went through bogey-free and made six birdies in Illinois.
Americans Brittany Altomare, Jaye Marie Green and Jessica Korda are joined by Canadian 2016 winner Brooke Henderson in a tie for second at five under.
On what is a congested leaderboard, Moriya Jutanugarn, Charley Hull, Laetitia Beck and Maude-Aimee Leblanc are a shot further back.
World number one and three-time champion Inbee Park battled to a one-over 73 in the first round.
Last year's winner Danielle Kang is alongside her in a tie for 71st, while Lydia Ko is back at two over.
The opening round featured two holes-in-one, Brittany Marchand (71) delivering at the 17th and Lexi Thompson (72) managing the feat at the sixth.
