SOUTHAMPTON, June 28, 2013 (AFP) - Kim, playing her first US Women's Open, had six birdies and no bogeys on the par-72 Sebonack Golf Club course to edge ahead of Park, who held the clubhouse lead for most of the day on five-under 67.
"This is my first time in the US Open and I didn't think that I was going to do it like this," said Kim, a seven-time winner on the Korean LPGA Tour.
Park, whose five titles in 2013 include major triumphs at the Kraft Nabisco Championship and the LPGA Championship, had six birdies and one bogey for sole possession of second place.
"I played very good today," Park said. "I hit the ball very good, didn't miss many fairways or greens.
"I was able to take some pins today where the USGA was a little generous on us today."
The US Golf Association -- not known for generosity in the set-up of its Open championships -- moved up the tees in anticipation of inclement weather, and Park took full advantage.
"Instead of hitting, like, five-irons, we were hitting nine-irons, and that was making the course much easier," she said. "I was actually able to go for some pins and give myself a lot of opportunities today. I made a lot of putts and didn't leave much out there."
Park opened her round with a birdie at the 10th hole, where she hit a wedge to about a foot and "just tapped in for birdie".
She picked up another stroke at the par-four 14th, rolling in a seven-footer.
After sinking birdie putts of five and 12 feet at the first and second holes and a 15-footer at the fourth, she made her only bogey of the day at the sixth, where she was in the rough off the tee and wasn't able to get up and down.
She bounced back with a birdie at the par-five eighth, where her chip from 30 yards left her a five-foot birdie putt.
As usual, Park was a model of calm throughout her round.
"I get my happy moments and I get my angry moments," she said. "But it's just a shot in golf, and you sometimes hit a good shot. You sometimes hit a bad shot. I don't think it's a big deal. You're excited inside, but you can't be too excited because you've got to play the next shot."
Four players shared third place on four-under par 68.
Sweden's Caroline Hedwall and South Korea's I.K. Kim both got as low as five-under, each bogeyed her final hole to fall back.
Sweden's Anna Nordqvist and American Lizette Salas both birdied their last two holes -- the eighth and ninth, to reach four-under.
Canada's Maude-Aimee LeBlanc and Chile's Paz Echeverria were a further shot back on 69.
Although Kim will take the lead into Friday's second round, the spotlight will remain on her illustrious compatriot Park, who is seeking to join an elite club of women golfers to win three major titles in a single season.
Babe Zaharias won all three majors in 1950, comprising the Titleholders Championship, Women's Western Open and the US Women's Open.
In 1961 Mickey Wright won the LPGA Championship US Women's Open and Titleholders but was third in the Western Open designated a major that year.
In 1986, Pat Bradley won the Kraft Nabisco, LPGA Championship and du Maurier Classic but missed out at the US Women's Open.
This year, the LPGA has designated five tournaments as majors: the Kraft Nabisco, LPGA Championship, US Women's Open, Women's British Open and the Evian Championship in France.
Leading first-round scores on Thursday in the US Women's Open golf championship (USA unless noted, par 72):
66 - Kim Ha-Neul (KOR)
67 - Park In-Bee (KOR)
68 - Anna Nordqvist (SWE), I.K. Kim (KOR), Lizette Salas, Caroline Hedwall (SWE)
69 - Maude-Aimee LeBlanc (CAN), Paz Echeverria (CHI)
70 - Jessica Korda, Catriona Matthew (SCO), Jennifer Rosales (PHI), Natalie Gulbis, Karine Icher (FRA), Yang Je-Yoon (KOR), Jodi Ewart Shadoff (ENG), Mariajo Uribe (COL)
71 - Feng Shanshan (CHN), Kang Hae-Ji (KOR), Pornanong Phatlum (THA), a-Brooke Mackenzie Henderson (CAN), Caroline Masson (GER), Sarah Jane Smith (AUS), Choi Na-Yeon (KOR), Stacy Lewis, Meena Lee (KOR), Lindy Duncan, a-Kim Kyung
72 - Juli Inkster, Paul Creamer, Cristie Kerr, Mika Miyazato (JPN), Ryann O'Toole, Yang Soo-Jin (KOR), a-Lydia Ko (NZL), Brittany Lincicome, a-Feng Yueer (CHN)