New Zealander Ko and South Korean Jang Ha-na were tied for the lead at seven-under, Ko after recording four birdies in 17 holes while Jang, the overnight pacesetter, was yet to tee off.
Japan's Haru Nomura and Malaysia's Kelly Tan were a further stroke back, Nomura having carded a six-under-par 66 to hold the clubhouse lead and Tan after completing three holes.
"I said, 'Hey, I've never been suspended where I have got one putt to go or I'm on the green," a smiling Ko, who is playign her first LPGA event of the year, told reporters.
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"Then the girls were saying, 'Ah, now that we said it it'll probably happen.' And guess what? It did. But what can we do about it? Not like we can play in really dangerous conditions."
Ko, who at 17 became the youngest golfer to hold top spot in the world rankings after tying for second at last year's Coates Golf Championship, was delighted to shake off the rusty play she had produced in her opening 69.
"I hit the ball really well today," said the 18-year-old, who is already a 10-time winner on the LPGA Tour. "I struggled a little bit with my driver yesterday, but today I hit all the fairways so I was super happy with that.
"I left a few putts out there where I did have good looks for birdies, but ... I’ve still got one more good look for birdie. I just got to stay patient."
Co-leader Jang, who made LPGA history last week with an albatross one, set the first-round pace after opening with a flawless seven-under-par 65.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)
