Inbee Park stretched her lead to two strokes at the Manulife Financial LPGA Classic with a third-round 66 at the Grey Silo course in Ontario.
The Korean led by one overnight ahead of compatriot Seo Hee-kyung, American Brittany Lang and China's Shanshan Feng, and added to her advantage over the former two as Feng slipped off the pace.
Park made six birdies, with just a solitary bogey at the par-three 17th, in a third strong round in succession. She has dropped just five shots over the course of the week, including at the first two holes of her opening round.
Her consistency was rewarded with a 14-under-par total, two better than Lang and Seo. The second Korean had five birdies with a bogey at eight while Lang left her run late, finishing birdie-birdie-eagle having played par golf to that point.
Sweden's Anna Nordqvist was two shots further back after a four-under-par 67, with each nine holes featuring three birdies and a bogey.
World number four Feng shot 70 to find herself in a group of four players at nine under, which also included Americans Nicole Hage and Sandra Changkija and Sweden's Karin Sjodin.
A British challenge failed to materialise, with Jodi Ewart five under after a one-over-par 72 and Karen Stupples back at two under after taking 73.
