American Stacy Lewis shot a course record 63 in the opening round of the Evian Masters in France on Thursday, her scorching form matching the 30-degree heat.
Runner-up behind Japan's Ai Miyazato last year, Lewis had a flawless nine-birdie round to lead by two shots from South Korea's Park Hee Young. Another South Korean, Lee Ilhee, was in third place on 66.
Lewis had seven birdies in a row from the seventh and then added more at the 17th and 18th for the terrific nine-under-par score.
Swede Helen Alfredsson, the only three-time winner, shot 63 on her way to victory in 2008, but Lewis's score counts as a new record as the course has been lengthened in preparation for the tournament becoming the fifth women's major next year.
"It's a great way to start," said Lewis, who won a major last year -- the Kraft Nabisco Championship.
"I love coming to Evian. You always feel so relaxed," she added.
"Today, I started pretty slowly and then it just clicked and I started making birdie after birdie. The seventh in a row at the 11th was from about 20 feet. I also just missed at 12. I've had six in a row before, but never seven."
Park, who made her big breakthrough with a debut win on the LPGA Tour at the Titleholders Championship last season, also had a blistering birdie run.
She made five birdies in a row from the fifth and had eight in all. Her only bogey was at the fourth and her great round came just days after she switched to a belly putter.
"I have never changed my putter in 15 years playing golf," said the 25-year-old. "I went over to the belly putter just 10 days ago and I was really nervous about using it.
"But it really worked well and everyone was telling me that Ernie Els won the Open with a long putter so it was probably a good thing to do. They were right.
"I also think it is nice to come back after a break. In the past couple of weeks I've been kayaking, cycling running and playing tennis. Just things away from golf to relax."
Feng Shanshan, the first Chines player to win a major -- the LPGA Championship in June -- dropped a shot at the long 18th but stayed well in touch on four-under-par 68. She was tied for sixth.
Following her win in the LPGA Championship in Rochester in New York State, Feng -- who wants to do for golf what compatriot Li Na has done for tennis -- was overwhelmed by the welcome she got when she returned to China.
"I am usually met by my family at the airport, but this time there were lots of people and photographers and posters of me on the walls. It was amazing," she said.
"I really do hope I can help introduce more young Chinese girls to golf and the win has given me so much confidence."
Japan's Ai Miyazato, the defending champion, opened with a 71, while the best of the six French players was Karine Icher, who had five birdies on the front nine in a 68.
But two big names struggled. South Korea's Choi Na Yeon, winner of the US Women's Open earlier this month, had a 75, and world number one Yani Tseng of Taiwan shot 76.