England's Mel Reid and 17-year-old high school student Megha Ganne kept their putters hot amid chilly conditions to card rounds of 67 and sit tied for the lead after the first round of the US Women's Open on Thursday.
Reid, who went out as part of the morning wave amid dense coastal fog in San Francisco, carded five birdies and a bogey to take a one-stroke clubhouse lead at four under early on at the major.
Her lead appeared safe until American amateur Ganne came out of nowhere in the afternoon to put on a putting clinic of her own.
Ganne pulled into a share of the lead with a birdie on the par-three 15th and took the lead on the next hole with her sixth birdie of the day on the par-five 16th.
But an errant tee shot on her final hole found the rough and the ensuing bogey dropped her back into a share of the lead.
Ganne, who played in the tournament two years ago as a 15-year-old, said taming her nerves was key to her success.
"I think the first time is nerve-racking for anybody - meeting your idols and being on the stage for the first time," she said.
"But the second time around, even the practice rounds, I wasn't as nervous."
Brooke Henderson, Megan Khang and Angel Yin are tied for third on three under.
Northern Ireland's Stephanie Meadow languishes nine shots off the lead at Olympic Club after carding a five-over par 76.
Meadow opened with consecutive bogeys before adding a third on the par-four fifth. A sole birdie followed on the sixth hole, but the 29-year-old went on to drop three more shots on the back nine of a tournament she sensationally finished third in on her professional debut in 2014.
A limited number of fans are on site at the 76th edition of the tournament, which because of the coronavirus pandemic had no fans in attendance last year.