South Korea`s Ryu So-Yeon fired a five-under par 67 Saturday to set a 54-hole tournament record and grab a four-shot lead after three rounds of the LPGA Canadian Women`s Open.
Ninth-ranked Ryu, the 2011 US Women`s Open champion, stood on 20-under 196 entering the final round at Ontario`s London Hunt and Country Club.
Ryu is bidding for a wire-to-wire victory, having led by five shots after 36 holes following a course record 63 in the opening round.
With 21 birdies against a lone bogey over the first three rounds, Ryu is already below the tournament record score of 18-under par by Norway`s Suzann Pettersen in 2009.
"I shot two-under and I feel like I lost 10 shots on the field," Pettersen said Saturday after birdie-filled rounds for top rivals.
Ryu, whose only other LPGA title came at the 2012 Toledo Classic, saw her course record matched by Spaniard Azahara Munoz, who shared second on 200 with South Korean Choi Na-Yeon, who shot 66.
World number two Park In-Bee, the South Korean star who captured her fifth career major title at last week`s LPGA Championship, was fourth on 202 with Sweden`s Anna Nordqvist another stroke adrift.
Ryu, who had 10 top-10 finishes without a victory last year, has nine more this year without lifting a trophy, adding to her desire to end the two-year drought.
After taking her first bogey of the tournament at the third, Ryu answered with back-to-back birdies at six and par-5 seven and began the back nine with another birdie on a par-5 hole.
Ryu birdied the par-3 13th, par-5 16th and par-3 17th as well to stay in front as rivals threatened to close the gap despite her success.
Munoz, whose last victory was in the 2012 LPGA Match Play Championship, helped Spain capture the International Crown team event last month in Baltimore and sizzled on the back nine with birdies on six of the last eight holes.
"It gives you a lot of opportunities," Munzo said of the course. "You definitely have to hit the fairways. The rough is super thick. If you hit the greens you have opportunities and I made really good putts today.
"When you start making putts, you can go really low."
Munoz reached 12 of 14 fairways and needed only 25 putts.
Choi matched her for second with birdies at 16 and 17 after starting with birdies on three of the firts five holes.