Anna Nordqvist moved a shot ahead of Scotland's Catriona Matthew in the third round of the Airbus LPGA Classic.
The Swede, 26, is 16-under-par after four successive birdies on the front nine, and six overall, helped her card 66 on Saturday.
By contrast Matthew, who led after the previous two rounds, struggled on the first nine holes at Mobile, Alabama.
The 44-year-old hit three bogeys before recovering with five birdies, while England's Charley Hull is tied fourth.
A third round 66 kept American Stacy Lewis in contention, two shots behind Nordqvist in third.
Hull, 18, is one of three players a stroke further back. The 18-year-old had been second going into the third round, but finished on 71 for the day, with two birdies and a bogey, to sit three shots behind.
She is joined by Americans Michelle Wie and Jessica Korda after they carded 66 and 69 respectively.
England's Jodi Ewart Shadoff, 26, hit 68 to go four shots off the lead, with South Korean trio Ryu So-yeon, Ji Eun-hee and Jenny Shin also on 12-under-par overall.