Red-hot Thompson chases Canada win

Thompson, 22, who won last month's Kingsmill Championship in Virginia, reeled off five birdies and no bogeys in a flawless display at Whistle Bear Golf Club.

Thompson's round left her with a 54-hole aggregate 199 at 17 under, one clear of fellow American Lindy Duncan, who also shot a 67 on Saturday.

A further shot back from Duncan is Chun In-Gee of South Korea, who remained in the hunt with a 68.

Thailand's Ariya Jutanugarn shot a blistering seven-under-par 65 to move into contention at 14 under, three off the lead, alongside Canada's Alena Sharp.

Ariya Jutanugarn of Thailand reacts after hitting her tee shot

Thompson completed her round with a birdie on the last but said consistency had been the key to another solid display.

"There was just more shot-making and some pins were pretty difficult to get to," she said.

"It was more just making pars and getting off the hole."

Duncan meanwhile -- who is 172 places behind world number four Thompson in the rankings -- will be looking for a strong final round on Sunday as she aims to improve on her highest ever finish, a tie for 16th.

"Hit my driver well today, and I would say I've been hitting fairways and hitting greens and really rolling the putter well," Duncan said.

"When I have gotten in trouble, I've been able to get up and downs for par. Those have been key up and downs."

Duncan now faces the prospect of playing in the final group on Sunday for the first time in her professional career.

South Korea's Chun meanwhile will be hoping to mount a final round charge as she aims to improve on three second place finishes this season.

The world number five posted five birdies before making bogey at the 17th.