Mariajo Uribe carded a 6-under 67 on Friday to grab a 1-stroke lead after two rounds of the Women's Australian Open.
Uribe completed two rounds at 15-under-par 131 at the par-73 Royal Canberra Golf Club.
First-round leader Lydia Ko shot 4-under 69. The 15-year-old amateur fell into a share of second place with Jiyai Shin, who posted a 67, at minus-14.
Kristie Smith (68) is alone in fourth at 10-under 136, while Beatriz Recari (69) is one shot back at minus-9.
Defending champion Jessica Korda (69) and world No. 1 Yani Tseng (71) are among six players tied for eighth at 7-under-par 139.
Uribe played the back nine first on Friday and opened with a birdie on the par-4 10th. She ran off seven consecutive pars before making birdie at 18 to turn at minus-11.
The Colombian caught fire around the turn with birdies at the second and fourth.
Uribe converted her fifth birdie of the day at the par-5 sixth. That gave her a share of the lead at 14-under. She came right back with a birdie at the seventh to move one stroke clear of the field.
The 22-year-old Uribe parred the final two holes to end one clear. She has played the first 36 holes without a bogey.
"I'm not hitting the ball that well, but I'm putting great, so it really helps out when you have to get an up and down and make birdies," Uribe said. "I went out just wanting to get in the competition after two months without playing, so it was a fun round. I made good putts and took advantage of the opportunities. So I feel pretty good."
Ko, who won the New Zealand Women's Open last week for her third professional title, parred her first two holes before converting a birdie effort on the par-3 third.
The teenager poured in three consecutive birdies from the fifth to jump to 14- under. She parred the next four holes.
Ko birdied the par-4 12th, but gave that stroke back with a bogey at the 14th. She closed her round with four straight pars.
"Obviously, I get mad when things don't go right, but I'm not the kind of one where I actually show my expectations," Ko admitted. "Just kind of boiling inside."
Shin, the reigning Women's British Open champion, notched back-to-back birdies from the 10th. After tripping to a bogey on No. 14, she carded three straight birdies from the 15th.
The Korean carded three more birdies on the front nine to climb to 15-under. However, Shin faltered to a bogey at the ninth, her last, to end one back.
"I made a couple of bogeys today, but I made more birdies. Well, I hit it okay, but just read it wrong," Shin said of her par putt at the last. "So I still have a good feeling at the moment and my tempo is good, so I just keep doing what I'm doing the next couple of days."
NOTES: Uribe won the 2011 HSBC Brasil Cup, which was an unofficial event, but does not own an official LPGA Tour victory ... The cut line fell at 1-under- par 145 with 82 players making it to the weekend ... Among those that missed the cut were Michelle Wie, Azahara Munoz, Brittany Lang, Karen Stupples and Sophie Gustafson.