New Zealand teenager Lydia Ko seized a one-stroke lead in the Canadian Women\'s Open on Saturday, setting her sights on becoming the youngest winner in LPGA Tour history. Ko, 15, fired an even-par 72 on the Vancouver Golf Club layout for an eight-under total of 208. She was one stroke in front of a quartet of players: American Stacy Lewis and South Koreans Jiyai Shin, Inbee Park and Chella Choi. Choi, who shared the overnight lead with Ko, carded a 73. Lewis climbed up the leaderboard with a 66, Shin posted a 69 and Park carded a 70. It was two further strokes back to Sydnee Michaels (69) and Moira Dunn (72) on 211. The South Korean-born Ko could also become the fifth amateur to win an LPGA title and the first since JoAnne Carner in the 1969 Burdine\'s Invitational. Ko won the US Women\'s Amateur championship a fortnight ago and in January whe won the New South Wales Open in Australia at 14 to become the youngest player to win an event on a professional tour. Lexi Thompson is the youngest LPGA Tour winner, taking the Navistar LPGA Classic last September at 16. Ko\'s round included three birdies and three bogeys. Her lead could have been a bit bigger but for a bogey at the par-four 18th, where she missed a four-foot putt for par. World number one Yani Tseng, who led after the first round, struggled to a two-over 74 on Saturday. The Taiwan star is tied for 21st at one-under 215.