Ko made two birdies and three bogeys in her third round as she once again competed well in a world-class field. She has all-but sewn up the leading amateur honours at the tournament as she holds an 11 shot lead over Japan's Yumi Matsubara.
Ko, who is the youngest winner on the Australian LPGA, Ladies European Tour and LPGA Tour, has continued her remarkable record of never missing a cut in 17 professional events.
Ko, who is No 22 on the official world golf rankings, has won three titles, finished runner-up three times and third once in professional fields. She has also finished as the low amateur in all three major championships she has contested to earn an amateur record that is one of the best ever seen in the game.
She will return home following her week in Japan to catch up on some school work. Her next event will be the LPGA Championship at the Pittsford Golf Club in New York, where she will contest her fourth major and look to become the youngest major winner in history.
American Morgan Pressel holds that record after claiming the 2007 Kraft Nabisco Championship at the age of 18 years, 10 months and nine days.
