A barrage of six birdies on the back nine, including three-in-a-row to finish, after going out in 34 gave her a one-shot advantage over her nearest challenger, Kim, In-Kyung at Kingsbarns Golf Links.
Unable to defend her title a year ago at Woburn due to injury, the seven-time major champion took advantage of lovely morning conditions to record her lowest round in a grand slam event. "My mom told me I needed to take my putter straighter back".
Park will need some more heroics come Sunday if she's to unsettle the frontrunner.
At four-over par, defending champion Ariya Jutanugarn missed the cut in her third consecutive major championship, due in large part to a second round 77 that included a nine at the par 3, 12th hole. "But I decided I had to be nice to myself".
It kept the Thai calm and focused as she made a move up the leaderboard with a five-under par, 67.
"If you look at most golfers, I don't think they look that good".
"It's my first season in America and I think I've missed five or six cuts by a shot - the difference from that to contending is very, very small out there". Over the last three days, she's made 17 birdies and an eagle while dropping just two shots - a new 54-hole scoring record for the Women's Open.
The 21-year-old from Bangkok won the major title by three shots over the tree-lined Woburn course - and she knows she faces a vastly different challenge at the windswept Scottish links.
Wie has played some of her best golf this year.
Wie's best result in the British Open was a tie for third on her debut as a 15-year-old at Royal Birkdale in 2005. Her first shot found sand by the green.
"I think I can now trust myself that my ball flight is good enough and strong enough".
Park didn't even bother showing up to the putting green until Saturday morning she was so concerned about her ball-striking.
"Now, I just want to enjoy tonight then whatever happens tomorrow, I'll take". "I'm just happy to be playing and happy to be playing at full capacity". As a result of grinding her teeth while asleep, the 22-year-old American is having "bad problems" with her temporomandibular joint. I had a rough day yesterday - I didn't play - but it was incredible how well I was hitting the ball today.
"I try to play level-headed all the time, whether I get a birdie or a bogey", said Hall, who intends to compete at the LPGA qualifying school later this year.