Sydney - On-fire Mexican Abraham Ancer battled howling winds to sink nine birdies and race to a five shot lead at the Australian Open Saturday, with Japanese amateur Keita Nakajima a surprise package in second.
World number 96 Ancer, who already has two top five finishes on the US PGA Tour this season, started two shots off the leaders but made an incredible run of five birdies at the sixth to 10th holes to take control.
Further birdies at the 16th and 17th ensured a superb 65 to be 13-under-par going into the final day.
Overnight frontrunners An Byeong-hun and Max McCardle slumped to 76 and 75 respectively to all but end their hopes of having their names engraved on the Stonehaven Cup alongside the likes of Jack Nicklaus and Rory McIlroy.
Nakajima stayed in touch with a battling 70, but the young gun has a huge task ahead to claim what would be a famous victory.
Australia veteran Marcus Fraser is at seven-under in third place with Keegan Bradley. Fellow American Matt Kuchar, who won last week in Mexico, is a shot further back.
Bradley called Ancer's round one of the best he had seen all year anywhere, given the wind, and the Mexican admitted it had been tough going.
"I had to stay patient and just keep the ball in play, and I was able to do that," said Ancer, whose stature is currently unrivalled among his countrymen.
"It was a very challenging round, but everything went my way, and whenever something didn't go my way, I managed to make at most a bogey, which out here is pretty good."
The 27-year-old has never been to Australia before and said winning the trophy "would mean the world to me", with only one previous professional victory on the web.com tour - a pathway to the PGA Tour - in 2015.
The softly-spoken Nakajima, who won gold at the Asian Games this year and finished second at the Asia-Pacific Amateur Championship last month, admitted he was battling nerves.
"Tomorrow will be a tough day, but I'll enjoy the 18 holes and really do my best," he said in broken English.
Bradley, who won the BMW Championships this year, stayed in touch but said he was "bummed out" by his finish, hitting two late bogeys to ruin his scorecard.
"Abraham's been playing really good golf. I wish I wasn't that far back obviously, but you never know," said the world number 30.
"This is a tricky little course. You can go out and shoot a low one out here, so I look forward to doing that tomorrow."
Leading third-round scores at the Australian Open at The Lakes in Sydney Saturday (par 72, AUS unless stated, *denotes amateur):
203 - Abraham Ancer (MEX) 69-69-65
208 - *Keita Nakajima (JPN) 70-68-70
209 - Keegan Bradley (USA) 72-66-71, Marcus Fraser 69-69-71
210 - Matt Kuchar (USA) 70-67-73, Dimitrios Papadatos 69-70-71, Cameron Percy 69-69-72, Aaron Pike 72-71-67
211 - Maverick Antcliff 73-69-69, Max McCardle 70-66-75, *David Micheluzzi 68-69-74
212 - An Byeong-hun (KOR) 67-69-76, *Takumi Kanaya (JPN) 70-70-72
213 - Mikko Ilonen (FIN) 73-72-68
215 - Cameron Smith 74-71-70
218 - Brandt Snedeker (USA) 73-72-73