"But I doubled it plus one," she giggled. "61, I am pretty pleased with."
After her opening hole stumble, Ko found her putting range and had just 26 putts as she broke the previous course low set by Mi Hyang Lee in last year's final round when she beat Ko by a single shot.
Ko's putting stroke filled with confidence as she converted a range of putts including a swinging left to right 30 footer on the 4th hole which began her initial run of four successive birdies.
She had only two pars on the opening nine which she closed with another birdie on the par 3 ninth. Playing partner, England's Charlie Hull, refused to wilt and she finished with an impressive 8-under par round.
The wind was gentle but temperatures were climbing quickly towards the predicted late 20's as the crowd swelled with news of Ko's fireworks.