Japanese rising star Ayaka Furue was the pace-setter at the Evian Championship as the 22-year-old shot a 63 to edge one clear of the field.
The eight-under-par first round from Furue saw her finish the day narrowly clear of American star Nelly Korda and Canada's Brooke Henderson, who both went round in 64 to share second place.
Henderson had an eagle three at her final hole, the ninth, to stake her early claim as the 24-year-old world number 10 bids to win a second major, six years on from landing the Women's PGA Championship as a teenager.
Korda had a clean round of seven birdies and no dropped shots, with the Olympic champion saying on Fox Sports: "I was just making putts. That's typically what I struggle with the most on this golf course. I've always figured out where to miss and where to not, in a sense, but the birdie putts are key out here and they were just rolling in today."
The 23-year-old Korda had a blood clot removed from her left arm in April and has gained a different view on her golf career, saying: "I think I'm a little bit more chill about it. I'm trying to remind myself I'm lucky to be out there and enjoying every moment."
Furue will be looking over her shoulder, but she has plenty of experience of winning on the Japanese tour so may not be intimidated by the prospect of leading going into Friday, even if she sits only 48th on the money list in her first full year on the LPGA Tour.
New clubhouse leader!— LPGA (@LPGA) July 21, 2022
Ayaka Furue birdies her last to get to 8-under! pic.twitter.com/AHFr03RlN2
She also finished fourth at this tournament in 2021, having qualified due to her success in Japan. Ai Miyazato was Japan's last winner of the Evian Championship, carrying off the 2009 and 2011 titles.
Defending champion Minjee Lee had a one-under 70 to be tied for 39th place, while American Cheyenne Knight was fourth on her own after a six-under 65, one shot better off than a group including 2015 winner Lydia Ko and Charley Hull.