Fifteen-year-old amateur Lydia Ko fired a career-best, 10-under 63 on Thursday to grab a 1-stroke lead after the opening round of the Women's Australian Open.
Ko, who won her third professional event last week, rattled off 11 birdies, an eagle and three bogeys in her round at the par-73 Royal Canberra Golf Club.
Mariajo Uribe carded a 9-under 64 and is alone in second place, one stroke clear of Jiyai Shin.
Ayako Uehara, Mi Hyang Lee and Rebecca Lee-Bentham share fourth place at minus-7, while Giulia Sergas is alone in seventh after a round of 6-under 67.
Women's world No. 1 Yani Tseng, who played alongside Ko and Michelle Wie, opened with a 5-under 68. She is one of six players tied for eighth.
Tseng ran off five birdies in a 6-hole span from the 12th, but had just one birdie and one bogey the rest of the way.
"It was fun to watch her play golf today. I mean she still looks 15. I don't know how she hit the ball so well," Tseng said of Ko. "I wasn't even that close to her when I was 15. I really enjoyed playing with her today, too. She pushed me up a little bit."
Ko, who won the New Zealand Women's Open last week, got off to a rough start as she drove into the trees on No. 10, her first hole. That led to an opening bogey. She came right back with a birdie on the 11th, and followed with birdies on each of the next three holes.
"After my bogey on my first hole, which was the 10th, I thought 'what's today going to be like?' But after a couple of birdies, I started to feel pretty comfortable," Ko admitted.
The teenager holed a wedge shot from 100 yards out on No. 15 to jump into the lead at minus-5. Ko's second to the par-4 16th ran through the green and that led to her second bogey.
Not to worry. Ko bounced back with birdies on the next two holes to make the turn in 6-under 30.
Ko had a chance at shooting 59, but the front nine plays to a par of 37 with three par-5s. She parred her 10th hole, the par-5 first.
"I've played good before and gone triple, par, bogey or whatever. I didn't really think about what I was going to shoot," said Ko if she thought about shooting 59. "It was one shot at a time."
She poured in three consecutive birdies from the second. After a par at the fifth, Ko birdied the par-5 sixth to get to 10-under.
At the par-3 eighth, Ko pulled her tee shot long, left of the green and failed to save par. She erased that mistake at the ninth, when she stuffed her approach shot at the par-4 within a foot of the hole.
Uribe had three birdies in the first five holes, before making eagle at the sixth. She birdied No. 10 to move to minus-6. Her final three birdies came between the 13th and 17th.
NOTES: Wie stumbled to a quadruple-bogey on No. 18, her ninth, en route to a 1-over 74, which left her tied for 99th ... Ko's 63 will not go as a course record because preferred lies rules were in play ... Lee-Bentham and Moriya Jutanugarn (70) shared medalist honors at Q-School last fall ... Defending champion Jessica Korda opened with a 3-under 70 and is tied for 22nd ... Maude-Aimee LeBlanc was disqualified for signing an incorrect scorecard.