Angela Stanford carded a third round five-under-par 67 to open up a four-stroke lead at the Bell Micro Classic.

Stanford signed for seven birdies to move onto 12-under, with Katherine Hull second at eight-under after a 68 which also included seven birdies and an eagle but a costly double-bogey at the last.

Starting the day two strokes behind overnight leader Cristie Kerr, Stanford began slowly by bogeying her third hole of the day before recording her first birdie two holes later.

She added a birdie at the seventh but was even at the turn after a bogey an the ninth.

Stanford carded five birdies over a flawless back, which included four straight birdies from 13.

"I started out kind of shaky, but settled in on the backside and was just fortunate to have some flags that we could go out and get some good numbers," Stanford said. "So I just really kind of got into a rhythm in the back.

"It might be the best back nine I've ever played."

Kerr led entering play on Saturday but struggled and plummeted down the leaderboard after a 76.

She fired a six-under 66 on Friday to take a two-stroke lead, but managed to three birdies on Saturday against five bogeys and a double-bogey five.

"I'm kind of disappointed, obviously, with the last hole, but I know if I start out strong tomorrow I'll be happy, and, obviously, see what happens at the end," Hull said. "The bottom line is I shot 68 and played pretty well. I only really had a couple bad swings. So you got to look at the positives, build on those and take that confidence into tomorrow."

Angela Park (69) and Shanshan Feng (70) sit tied for third at six-under.