|LPGA Tour Swinging Skirts tournament leaderboard, San Francisco|
|-9 B Henderson (Can); -7 N Yeon Choi (S Kor); -6 S Yokomine (Jap), Y Cindy Feng (US); -5 H Na Jang (N Kor); M seo Kwak (S Kor), L Ko (NZ), J Granada (Par); Selected others: -4 S Lewis (US); -3 C Hedwall (Swe); +3 L Davies (Eng)|
Teenager Brooke Henderson claimed a tournament record score at the halfway stage of the LPGA Tour's Swinging Skirts tournament in San Francisco.
The Canadian, 17, recorded a seven-under-par 65 to take a two-shot lead from Choi Na-yeon at the halfway stage.
It gave Henderson a nine-under second-round total of 135, breaking Stacy Lewis's 2014 record by three shots.
"It's pretty cool," she said at the Lake Merced Golf Course. "This course is tough, and conditions are tougher."
Henderson is aiming for her maiden Tour victory and has had to rely on sponsor exemptions to get into tournaments after failing to earn a card in qualifying school.
Her round included six birdies and an eagle although she stumbled to her first and only bogey of the week at the par-four fifth.
Asked if she was ready to win her first big tournament, Henderson said: "I think I'm ready.
"Yeah, 17 is young. As you've seen with Lydia Ko and Lexi Thompson and even Jessica Korda, there are a lot of great names that have been able to do it. I'm hoping that I'm one of them."
First-round leader and defending champion Ko of New Zealand celebrated her 18th birthday with an even-par 72 to finish tied for fifth.
South Korea's Choi carded a four-under 68 to seize sole possession of second place.