American Amy Olson fired a bogey-free 6-under-par 65 to take a two-shot advantage after three rounds at the Evian Championship in France on Saturday.
The 26-year-old American started the day with a share of halfway lead with three others but finished at 14 under overall.
Olson, who secured a tied ninth finish at the ANA Inspiration earlier this year, sank four birdies and a superb eagle at the ninth to steer clear of the chasing pack.
"I think the biggest thing that I like about major championships is how it forces you to bring your best game," she said.