Polly Mack shot a nine-under 63 on Thursday in perfect morning conditions at Columbia Edgewater to take the first-round lead in the Portland Classic.
Winless on the LPGA Tour, Mack opened with birdies on the 10th and 11th - her first two holes - and eagled the par-5 12th.
The 25-year-old German player added four birdies on the front nine, closing with two in a row.
With the Olympics next week in Paris, no one from the top 30 in the world ranking is in the field. The lone Olympian in the field is Aditi Ashok of India, who had a 70 in the afternoon.
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"Pretty flawless round," Mack said. "It seemed so easy out there today. Very nice start and that just kept me pretty calm."
German countrywoman Caroline Masson was a stroke back with Nataliya Guseva, Samantha Wagner and Hyo Joon Jang.
Playing in the afternoon, the 35-year-old Masson played the back nine in seven-under 29.
"I think golf is funny," Masson said. "This year has been a little bit difficult the last few weeks. Sometimes you feel like you get nothing going and today I actually got out of position a couple times and holed out from the bunker and chipped in on the next."
The 21-year-old Guseva, the first Russian to earn an LPGA Tour card, was in the morning wave with Wagner and Jang.
"Probably one of the best times for me on the LPGA when I was just really like going, talking, not even paying attention to my game," Guseva said. "I was just like hitting it well and knocking it in."
Emma Talley shot a 65 in the afternoon to match morning starter Daniela Darquea of Ecuador while defending champion Chanettee Wannasaen, who won the Dana Open two weeks ago in Ohio for her second LPGA Tour title, shot 68.
Lauren Coughlin, the CPKC Women's Open winner Sunday in Calgary, Alberta, for her first LPGA Tour title, had a 66 in the morning.
Angel Yin also was at 66 with Sofia Garcia, Grace Kim, So Mi Lee, Pajaree Anannarukarn, Cheyenne Knight, Jenny Shin and Dewi Weber.
Weber qualified for the Olympics under International Golf Federation standards, but the Dutch Olympic committee declined to send her to France.
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