MELBOURNE, Australia -- U.S. Women's Open champion So Yeon Ryu shot a 4-under 69 on Friday to take a one-stroke lead over fellow South Korean player Hee Kyung Seo in the LPGA Tour's season-opening Women's Australian Open.
Ryu, a playoff winner over Hee in July at the Broadmoor in Colorado Springs, Colo., had a 6-under 140 total on Royal Melbourne's Composite Course, the 2011 Presidents Cup venue that is hosting a women's professional event for the first time.
"Today, my plan was always just par," Ryu said. "This course is really tough."
Seo shot a 66, the best score in the first two days of the tournament also sanctioned by Australian Ladies Professional Golf and the Ladies European Tour. She had nine birdies and two bogeys.
"I was trying not to be afraid of the course," Seo said. "Sometimes when I play this kind of course, I am afraid too much about the course and can't play my game and can't make my own swing. But today I was thinking about routine process and coming on the target and that worked really good."
American Stacy Lewis, the Kraft Nabisco winner, birdied Nos. 12 and 13 to take the lead at 7 under, but followed with a triple-bogey 7 on No. 14 and bogeys on Nos. 15 and 16. She eagled the par-5 17th and closed with a par for a 73 to finish at 4 under.
American Jessica Korda, England's Melissa Reid and Paraguay's Julieta Granada also were 4 under. Korda had a 70. Her father, Petr Korda, won the 1998 Australian Open tennis title. Reid shot a 71, and Granada had a 72.
Ryu and Seo were the only players to break 70 Friday after Lewis and Sarah Kemp topped the leaderboard Thursday at 69. Only nine players were under par after 36 holes, with long-hitting American Brittany Lincicome, Canada's Lorie Kane and Germany's Sandra Gal at 1 under. Seventy-three players at 7 over or better advanced to the weekend.
Ryu works with Australian instructor Ian Triggs.
"He is a coach, but feels like a father," Ryu said.
Triggs has helped her adjust to Royal Melbourne's fast greens.
"Sometimes I lose concentration and he wanted me to feel the putts on the putting green," Ryu said. "I practiced just feeling putts. Sometimes, if I am really nervous, my routine is so fast. I just slowed down and really focused on my ball."
The 22-year-old Ryu tied for second last week in the Australian Ladies Masters at Royal Pines, a stroke behind the Netherlands' Christel Boeljon.
Seo also has a helpful Australian connection in caddie Dean Herden.
"He is not just a caddie for me," Seo said. "He is like a brother, a dad sometimes, a friend. He makes me really comfortable all the time. Sometimes he pushes me hard. Not on the course, but in training. I am very happy and very thankful for him."
Two-time defending champion Yani Tseng was even par after a 76. She had a quadruple-bogey 8 on the seventh hole and bogeyed the next two holes.
"I almost cried," Tseng said. "But no I didn't. I hung in there and I did a good job. ... I'm glad I was able to fight back on the back nine."
On the seventh, the top-ranked Taiwanese star pulled her drive left into an unplayable lie. She took a drop, but was still in the deep grass, and needed three more shots to reach the fairway. She hit her sixth shot onto the green and two-putted.
"My first instinct was to go back to the tee," Tseng said. "I should have decided that way, too, to save a couple shots."
Tseng won the tournament, sanctioned by the LPGA Tour for the first time this year, the last two seasons at Commonwealth Golf Club. She won 12 worldwide titles last year, including major victories in the LPGA Championship and Women's British Open.
American Lexi Thompson, celebrating her 17th birthday, was 2 over after her second 74.
Four-time champion Karrie Webb was 4 over after a 75.
Fourteen-year-old New Zealand amateur Lydia Ko also was 4 over after a 76. She won the New South Wales Open two weeks ago to become the youngest winner of a sanctioned professional tour event.
Second-ranked Suzann Pettersen followed her opening 80 -- the second-highest score of her LPGA Tour career -- with a 71 to make the cut. Fourth-ranked Cristie Kerr survived the cut on the number at 7 over with rounds of 75 and 78.
Former UCLA star Stephanie Kono had a miserable start to her LPGA Tour career, shooting 78-92. She played her final nine holes in 16-over 52, carding 8s on the par-5 second and par-3 third and a 7 on the par-4 sixth.