Colombia's Mariajo Uribe moved ahead of New Zealand's teen sensation Lydia Ko when she fired six-under-par 67 to lead the Women's Australian Open by a single stroke on Friday.
Uribe, in the opening event of the US LPGA season, headed into the weekend holding a narrow advantage over first-day leader Ko, who is an amateur and is aged just 15, and world number eight Shin Ji-Yai of South Korea.
The Colombian drilled six birdies, including four over her last eight holes, to top the leaderboard at 15-under-par 131 over 36 holes at the par-73 Royal Canberra Golf Club.
Ko, who carded a scintillating 10-under-par 63 on day one, hit 69 in her second round to share second with Shin. Despite the teenager's famously calm appearance, she admitted she is "boiling inside" when shots go awry.
"I mean, obviously I get mad when things don't go right, but yeah, I'm not the kind of one where I actually show my expectations," said Ko. "Just kind of boiling inside."
Uribe, 22, is bogey-free in her first two rounds - including a 64 on day one - and she said she had not played such flawless golf in years.
"I did something like this back when I was like 17 and I was an amateur, like at home in Colombia," said Uribe.
"The first day I shot six under, the second day 10 under with no bogeys. So that was probably the last time. That was in 2007.
"So it's been a long time without having bogeys, especially in a course like this where the rough is tougher. I mean, I've just been putting awesome."