Newly crowned world No.1 Lydia Ko shot a second straight three-under par 70 to grab a share of the halfway lead at the women's Australian Open, the third event on this year's LPGA Tour.

After parring the first nine holes, the 17-year-old from New Zealand had a far more adventurous back nine that featured an eagle, three birdies and two bogeys.

Ko was furious with herself after only taking a par at the 14th hole, which she eagled the previous day, but made amends when she eagled the par-four 15th, holing out with a nine-iron from 125 metres (136 yards).

"That anger led me to hit an aggressive drive on the 15th," Ko said. "I was so upset from the hole before that I gambled.

"A little bit of anger is good because it lets the steam out, whereas sometimes I've had experiences where I've kept it in and it's definitely not helped me."

South Korea's Jang Ha-na, who finished third at last year's Evian Championship, joined Ko and Thai teenager Ariya Jutanugarn (71) in a three-way tie for the lead at six-under after shooting 69, the best round of the day.

England's Charley Hull was outright fourth at four-under, one shot ahead of South Korean Amy Yang and American Jessica Korda, who won the 2012 Australian Open champion, the last time the event was played at Royal Melbourne