Park, who had the cyst on her middle finger drained, made up for lost time with five birdies in her first eight holes.
“I was a little bit worried about not practicing for a few days, but I had a good day today, especially the front nine,” Park said.
“It was a good putting day. Obviously on the back nine I could’ve shot a little bit better but I have three more days to go and I just got to work on my ball striking."
Park needs at least an eighth-place finish to keep the Rolex Player of the Year race alive against frontrunner Lydia Ko.
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Stanford used a hot putter to get into contention after enduring a bad bout of jet lag travelling to Mexico City after losing in a three-way playoff on Sunday at the Japan Classic.
The American said she felt like she had been "hit by a train” but did not think it would be an issue the rest of the week.
“I was putting really well again today,” she said. “Had 24 putts again today and did that two times last week in Japan."
Amateur Gaby Lopez of Mexico, among seven players tied for fifth at one-under 71, had no need for her putter on the par-three fifth.
“I hit a 170-yard shot perfect and it landed like three paces on and jumped and landed just right, right into the cup,” Lopez said.
(Reporting by Larry Fine in New York; Editing by Peter Rutherford)
