SAN MARTIN, Calif. -- Mirim Lee, ranked No. 32 in the world, grabbed the first-round lead in the U.S. Women's Open, taming CordeValle Golf Club with a record-tying, 8-under-par 64 on Thursday.
Lee became the fifth player overall and first since 1999 in U.S. Women's Open history to shoot 8 under par in any round. Lee came within one shot of tying Helen Alfredsson's record for the lowest 18-hole score in the tournament of 63, set in the first round in 1994 at Indianwood in Lake Orion, Mich.
"Easy round," said Lee, a South Korean, who teed off early in a group with Kerr.
That's not something you often hear after any round in the U.S. Women's Open, and Kerr said she expects course conditions to get tougher as the week goes on.
"We played in the morning and took advantage of it," Kerr said of the cool weather and softer greens. "Obviously, Mirim had almost a career round today. I definitely expect it to change.
"I don't think the USGA likes somebody shooting 8 under on their golf course. So you have to expect it to change, and if it doesn't, then you'll have opportunities to score.
"It's a very straightforward course. The rough's not great. ... If you're hitting the fairways, you can certainly score."
Kerr, who won the U.S. Women's Open in 2007, had seven birdies and two bogeys. Minjee Lee had an eagle on the par-4 sixth, four birdies and one bogey. Yang had six birdies and one bogey.
Mirim Lee had 10 birdies and two bogeys, including one on the par-4 10th, her first hole of the day. She birdied six of the nine holes on the front nine.
"I think everything was good," the leader said of her game. "Driver was good, irons good. A couple missed putts, but not bad. It was good."
Lee has only two career victories on the LPGA Tour and none since 2014, but she tied for fourth at the Women's PGA Championship this year, playing well in a major.
Twenty-three players who teed off in the morning broke par in the first round. Yang was the only golfer who teed off in the afternoon who finished the day in the top seven.
Many of the world's top-ranked players began their rounds in the afternoon when the greens were drier and faster and the wind was stronger.
Top-ranked Lydia Ko, who played in a marquee group with No. 2 Brooke Henderson and No. 4 Lexi Thompson in the afternoon, finished 1 over. Henderson finished 4 over and Thompson 2 over. None of the three could get untracked, and all three struggled on the greens.
Ko saw Lee's 8-under score and was amazed.
"Mirim, I don't know what course she played," Ko said, smiling. "Maybe the ladies tees, maybe a different course. She played fantastic. I saw she made two bogeys and still shot 8 under, so it's very impressive. She must have hit a lot of fairways and made good putts, and that's the key."
NOTES: Defending champion In Gee Chun of South Korea, who teed off in the morning, shot a first-round 73. She had one birdie and two bogeys. ... South Korea's So Yeon Ryu, who won the 2011 U.S. Women's Open, was 4 under entering her final hole Thursday but took a triple-bogey 8 on the par-5 ninth and finished with a 71. ... Four amateurs came in at even par, including the world's top-ranked amateur, Hannah O'Sullivan of Chandler, Ariz.