The fifth-ranked South Korean star’s remarkable round put her at 8 under for the tournament, giving her a six-stroke lead over Amy Yang.
Only four players ever have posted a lower round in the Open, and the 65 tied the lowest third-round score in the event’s history. “I couldn’t believe how I got eight birdies today,” Choi said. “But I did. And I’m very happy, and I’m very satisfied and I’m very excited.”
As Choi surged despite windy conditions, Michelle Wie faded, shooting a 6-over 78 to fall to 2 over. Wie shot a 66 in the second round and came into the day a stroke behind second-round leader Suzann Pettersen.
“It was a lot of fun being in contention,” Wie said. “I’m still not out of it. Don’t count me out just yet.”
Pettersen also shot 78 on Saturday and slid to 1 over, but still hoped to get back into contention.
“You know what, there’s birdies out there,” she said. “I think the wind is going to be a little bit less tomorrow from what I’ve seen.
“So if you get off to a hot start, hopefully put a number down early in the clubhouse. Who knows?”
Yang had a 69. Choi and Yang were the only players to break 70 in the round.
“I’m just going to keep being patient tomorrow, try to do my best,” Yang said.
Lexi Thompson, Mika Miyazato and Sandra Gal were tied for third at 1 under. The 17-year-old Thompson had a 72, Miyazato shot 73 and Gal had a 74.
“Seven under at an Open is pretty good, I would say,” Thompson said about Choi’s round. “So she’s leading by a good amount, but I’m still going to go for it.”
Top-ranked Yani Tseng struggled, shooting a 78 and fading to 8 over.
Tseng said she had trouble feeling comfortable with her club selection at times as she tried to deal with the wind and tough pin placements.
And Tseng said she didn’t see too many opportunities for low scores out there, adding, “Except Na Yeon.”
Choi has five career LPGA Tour victories. She tied for second in the 2010 U.S. Women’s Open.