WILLIAMSBURG, May 16, 2014 (AFP) - Ernst's blazing round included an eagle at the par-five third hole along with five birdies and a bogey for her best round since she posted a 62 at the Safeway Classic last year.
"Gave myself a lot of looks," Ernst said. "Hit a lot of greens and made it really easy on myself out there on a day when it was pretty windy and it could kind of get away from you a little bit."
Munoz said the winds were "tricky," even if they didn't seem to bother her.
"The pins were somehow accessible," said Munoz. "Obviously the course is playing much shorter than normal because it's warmer and drier. The greens roll nice, so it's really nice to putt. If you hit a good putt, it's going to go in."
Munoz said the closest she came to a bogey all day was at her second hole, the 11th. She was in a bunker and got up and down, draining a 10-footer for par.
The leading duo were one shot in front of South Korean Park Hee-Young.
It was a further stroke back to Thailand's Thidapa Suwannapura and Americans Brittany Lang, Cristie Kerr, Kathleen Ekey, Danielle Kang, Lizette Salas and Lexi Thompson, all on 67.
Park's 66 was her best round of the year, during which she has battled a painful wrist.
She took eight days off after her last start at the North Texas Shootout earlier this month and said physical therapy, acupuncture and ice treatment have her feeling better.
"Everything is pretty good," Park said. "I made a lot more putts. I practiced a lot of long distance putts and I made quite a bit of long putts."
Kerr, the defending champion, was determined to tee it up even after she had to withdraw from Wednesday's pro-am because of illness and ended up in hospital.
She was diagnosed with heat exhaustion and a possible infection and received intravenous fluids.
Even though her preparations were disrupted, Kerr coped admirably with the rising winds to put herself in contention.
"I hung in there, made some good birdies and kind of got it going in the right direction after the 10th hole," Kerr said.
Leading first-round scores on Thursday in the US LPGA Kingsmill Championship (USA unless noted, par-71):
65 - Azahara Munoz (ESP), Austin Ernst
66 - Park Hee-Young (KOR)
67 - Thidapa Suwannapura (THA), Brittany Lang, Cristie Kerr, Kathleen Ekey, Danielle Kang, Lizette Salas, Lexi Thompson
68 - Jessica Korda, Yani Tseng (TPE), Sandra Changkija, Dori Carter, Ai Miyazato (JPN), Sarah Jane Smith (AUS), Alejandra Llaneza (MEX)
69 - Kris Tamulis, Katherine Kirk (AUS), Jenny Shin (KOR), Haru Nomura (JPN), Joanna Klatten (FRA), Gerina Piller, Line Vedel (DEN), Sandra Gal (GER), Meena Lee (KOR), Alena Sharp (CAN), Brittany Lincicome