SYDNEY, Feb 16, 2013 (AFP) - Ko, who became the tour's youngest winner at last year's Canadian Women's Open, and Shin, South Korea's world number eight, opened up a commanding six-shot lead with matching three-under-par rounds at Royal Canberra Golf Club.
Coincidentally, the two were also paired in the last round of the Canadian tournament in August, when Korean-born Ko smashed US star Lexi Thompson's record by winning at the age of just 15 years, four months and two days.
Thompson was 16 years and eight months when she won the 2011 Navistar Classic, meaning victory on Sunday would make Ko the only player to win twice on the LPGA Tour before her 16th birthday, which is in April.
If not for two bogeys among her five birdies, Ko could have held the outright lead and despite scores of 63, 69 and 70 for her total of 17-under-par 202, she felt she had played better on her way to victory in Canada.
"I think when I played the best was at the Canadian Open," she said, according to the US LPGA website. "That week it felt like it went easily. That week I didn't really feel the pressure of wanting to win, because it was an LPGA event.
"So even up until the last hole I didn't know that I would win, so in that kind of situation it was pretty much when I was hitting the best."
Shin trailed in five shots behind Ko in Vancouver last year, but she was hopeful of a better result as she seeks her third win in her past seven LPGA appearances, and 11th overall.
"Well, I really look forward to tomorrow because I really enjoyed the last three rounds," said Shin. "And then I know I'll play a really young golfer.
"But I have more experience than her. I have a really good feeling with my swing and tempo, so I just give focus to each of my shots."
Spain's Beatriz Recari was alone in third spot behind the two leaders, with Taiwan's world number one Tseng Yani among a group two shots further back and eight off the pace on a total score of 210.
Round three scores from the US LPGA Women's Australian Open at par-73 Royal Canberra Golf Club on Saturday:
202 - Lydia Ko (NZL) 63-69-70, Shin Ji-Yai (KOR) 65-67-70
208 - Beatriz Recari (ESP) 68-69-71
210 - Gwladys Nocera (FRA) 74-71-65, Carlota Ciganda (ESP) 71-70-69, Moriya Jutanugarn (THA) 70-70-70, Tseng Yani (TPE) 68-71-71 Mariajo Uribe (COL) 64-67-79
211 - Lee Il-Hee (KOR) 73-69-69, Anna Nordqvist (SWE) 72-70-69, Stacy Prammanasudh (USA) 70-71-70, Dewi Claire Schreefel (NED) 70-72-69, Vicky Hurst (USA) 69-72-70, Sarah Jane Smith (AUS) 68-70-73
212 - Whitney Hillier (AUS) 74-69-69, Jennifer Rosales (PHI) 74-69-69, Ashlee Dewhurst (AUS) 73-70-69, Stacy Lewis (USA) 69-74-69, Katherine Hull-Kirk (AUS) 68-73-71, Danielle Kang (USA) 71-71-70, Rebecca Artis (AUS) 72-67-73, Gerina Piller (USA) 72-67-73, Giulia Sergas (ITA) 67-72-73
213 - Paola Moreno (COL) 74-71-68, Chella Choi (KOR) 74-69-70, Lexi Thompson (USA) 72-71-70, Austin Ernst (USA) 69-74-70, Belen Mozo (ESP) 71-71-71, Minjee Lee (AUS) 70-71-72, Brittany Lincicome (USA) 71-70-72, Jenny Shin (KOR) 71-69-73, Ayako Uehara (JPN) 66-73-74, Holly Aitchison (ENG) 70-68-75