England's Jodi Ewart Shadoff carded a first-round 64 to take a two-shot lead at the LPGA Mediheal Championship.
The 34-year-old, seeking her first professional Tour win, made an eagle and seven birdies in an eight-under-par start at the Saticoy Club in Somis, California, on Thursday.
"I gave myself a lot of opportunities and felt really comfortable and relaxed with the putter today," she said.
China's Ruixin Liu and America's Alison Lee are two shots behind in second.
Another American, Danielle Kang, playing only her fifth tournament after treatment on a spinal tumour, is among three players a shot further back.
Starting her round on the back nine, Ewart Shadoff reached the turn at five-under after eagling the par-five 14th and later reeled off four birdies in the final five holes.
The world number 93 is yet to win a title in 12 seasons on the LPGA Tour but has recorded 27 top-10 finishes and her fine start comes just days after compatriot Charley Hull won at The Ascendant.
"I think everything was just clicking - the putter just got hot and everything was flowing," Ewart Shadoff added.