Lydia Ko isn't used to looking so far up the leaderboard and will know she has a lot of ground to make up if she is to contend for this year's US Open.

The world No 1 shot a 1-over 73 at San Martin, mixing three birdies with four bogeys. It left her in a share of 52nd, nine shots off the lead held by South Korea's Mirim Lee who carded an impressive 8-under 64. Lee held a three-shot lead over South Korean Amy Yang, American Cristie Kerr and Australia's Minjee Lee.

What will encourage Ko is the fact a lot of the other big names struggled, including Brooke Henderson (+4), Sei Young Kim (+3), Lexi Thompson (+2) and Stacey Lewis (-1). Defending champion In Gee Chun was level with Ko on 1-over par.

"I don't know what course she played, maybe the ladies tees, maybe a different course," Ko said of Lee. "But she played fantastic. We were checking the leaderboard, she made two bogeys and still shot 8-under. It's very impressive. She must have hit a lot of fairways and made good putts. I think obviously that's the key."


Lee is the first woman to shoot that much below par at the US Open since Lorie Kane and Becky Iverson did it in the second round in 1999 at Old Waverly in Mississippi. The lowest total score in a round in US Open history is a 63 by Helen Alfredsson in 1994 at the par-71 Indianwood in Michigan.

The San Martin course largely favoured those who played in the morning, like Lee, with the exception of Yang who his the low round of the afternoon with a 5-under 67. Yang is a two-time US Open runner-up.

The greens are likely to quicken up as the tournament progresses and the wind could also become a significant factor.

Ko started on the back nine and was 2-over after four holes. She recovered with birdies on the 14th and 15th to make the turn even par but immediately dropped a shot on the first. She made up ground with a birdie on the par-five third but dropped another shot on the seventh.

Ko hit only 11 greens in regulation, which contrasted with Anna Nordqvist who hit every green in regulation today, a first in the history of the US Women's Open.