Along the way, she managed to outscore her playing partner and seven-time major winner Karrie Webb. The Australian great, who has 52 career wins to her name, could only manage a two-over par 75 in the tough conditions.
"It was playing hard here in any case but the winds were tough and came from a completely different direction today," Ko's coach Guy Wilson said.
"Yesterday Lydia hit a driver and eight iron into the 18th but today it was a driver and three-wood and she was still short."
He said the key today was accuracy and patience, particularly on the more challenging front nine.
"Lydia was outstanding. She hit all nine greens going out. She made two birdies and was unlucky with a couple of others."
Wilson said Ko was tired after her fourth tournament in a row and was looking forward to recharging the batteries for next week's New Zealand Open at Pegasus near Christchurch.