Laura Diaz fired a six-under-par 65 to make the early running after the first round in the Canadian Women’s Open at the Royal Mayfair Country Club.
After shooting a two-under-par 34 on the back nine, Diaz scorched the greens with a 31 on the front nine and finished with three birdies in her last four holes to complete a bogey-free round.
Diaz, who had finished 12th or better in three straight tournaments before missing the cut at the Women’s British Open at St. Andrews two weeks ago, is seeking her first tour victory since 2002 and the third of her career.
Kelli Kuehne and South Korea’s Kyeong Bae are tied for second place, one shot behind Diaz at five under.
Kuehne has missed the cut in four consecutive tournaments and seven of her last eight while Bae is searching for her fourth top 10 finish of the season and the first tour victory of her career.
Lorena Ochoa, who won her first major title at the British Open on August 5, shot a one-under-par 70.
The world number one is looking to add to her tour-leading four victories and 14 top-10 finishes in 17 events this season.
Cristie Kerr, who won this event in astounding fashion last year by overcoming an eight-shot deficit in the final round to beat Angela Stanford by one stroke, shot a two-under-par 69 to finish the day in three-way tie for 14th place.
Kerr, third on the money list, has struggled since winning the US Open on July 1 and has failed to finish higher than 33rd in her last four tournaments.
Alena Sharp leads the seven-strong contingent of Canadian Tour members after firing a one-under-par 70 and is tied with 10 other players – including Ochoa - for 17th place.