China's Yin Ruoning fired eight birdies in a career-low LPGA round of seven-under 64 on Friday to grab a share of the second-round lead with Kim Hyo-joo at the Los Angeles Open.
Yin, 20, teed off on the 10th at Palos Verdes Golf Club and was three-under through her first eight holes.
She picked up four birdies in a five-hole stretch, including three straight at the fifth, sixth and seventh on the way to a 10-under par total of 132.
Kim, whose five LPGA titles include a major at the 2014 Evian Championship, carded her second straight 66, posting five birdies without a bogey.
Yin, playing the second event of her second LPGA campaign, was impressive on the greens, needing just 24 putts.
She had seven straight one-putts on the first through seventh holes, but she said the real key to her round was ball-striking.
"I felt my game was in a pretty solid spot right now. I can strike the ball well and my approach shot is pretty good," she said.
"Last year I only play fade with every shot. This off-season I was working on maybe hitting a little draw, and I think that works," she said.
Kim had two birdies on the front nine and three coming in, taking advantage of all three par-fives.
But she said avoiding a bogey was key.
"There were a couple situations actually where I could have carded a bogey, but in those instances my putter worked well," she said.
The leading duo were one stroke in front of Japan's defending champion Nasa Hataoka, who posted a 66. Canadian Maude-Aimee Leblanc was in fourth on 134 after a second straight 67.
South Korean Lee Mi-hyang, the Monday qualifier who led after the first round, slipped seven shots off the pace with a three-over par 74.
LPGA LOS ANGELES OPEN SCORES
132 - Yin Ruoning (CHN) 68-64, Kim Hyo-joo (KOR) 66-66
133 - Nasa Hataoka (JPN) 67-66
134 - Maude-Aimee Leblanc (CAN) 67-67
135 - Lilia Vu 69-66, Megan Khang 66-69
136 - Jennifer Kupcho 72-64, Patty Tavatanakit (THA) 69-67
137 - Lizette Salas 73-64, Charley Hull (ENG) 68-69, Perrine Delacour (FRA) 68-69
138 - Atthaya Thitikul (THA) 72-66, Frida Kinhult (SWE) 71-67, Hannah Green (AUS) 71-67, Nelly Korda 68-70