She might be one of the youngest players contesting the US Women's Open but Lydia Ko has always played beyond her years.

The 19-year-old world No 1 was in the unfamiliar position of being tied for 52nd heading into today's second round at CordeValle, after a 1-over 73 on Friday. Eighteen holes later, we was in a share of fourth, only three shots behind leader Sung Hyun Park of South Korea.

Not that it started all that well for Ko. She bogeyed her first hold before stringing together three-straight birdies starting at the third. She added two more birdies before capping her round with the seventh of the day at the par-5 18th. Ko hit the joint lowest round of the day with Park, a 6-under 66.

"My birdie on three kind of turned the round around and making the string of birdies definitely helped," she said. "Just to know that this is the first time I was under par for the tournament kind of put myself in a positive position. I just tried to enjoy it out there."


While contending in a major is a mostly new experience for Park, Ko is an old hat at it. She won the Evian Championship last September to become the youngest woman ever to win a major and followed that up with her second at the ANA Inspiration this year.

Ko then lost a playoff to Brooke Henderson in the KPMG Women's PGA Championship in Washington last month.

"I think the more I play, I think the more I get used to it, especially at these majors where the courses are tough," Ko said. "You need to stay patient. I think that's the big key I've been learning, just keep my head high and just enjoy it out here."

Henderson has not had as much luck following up her major success. The world's second-ranked player hit two bogeys on the back nine to shoot a 1-under for the round that left her three over for the tournament and one shot inside the cut line. No 4-ranked Lexi Thompson, who also played with Ko and Henderson, as also at 3-over.

Koreans Amy Yang (71) and first-round leader Mirim Lee (74) were second, two shots behind Park and one ahead of Ko and Japan's Haru Nomura.