Pak, who has to complete four events to qualify for the Hall of Fame, was at even par after 13 holes. She birdied her final four holes with putts from a tap-in to 3m.
"I'm happy the way I finished but it's still three more days to go," Pak said.
Park, an 18-year-old South Korean who was born in Brazil, had four birdies and no bogeys. She leads the tour rookie standings with three top-20 finishes, including a tie for third.
Choi had five birdies and a bogey. The second-year US LPGA player has four top-25 finishes.
RSS