Rookie Angela Park and Stacy Prammanasudh are tied for the lead heading into Friday's second round of the Fields Open.
Each shot a 6-under-par 66 in Thursday's first round. They lead South Korean Se Ri Pak and Francella Meaghan by one stroke and Kyeong Bae by two shots.
The 18-year-old Park, who hails from Torrance, California and is the youngest competitor in the field, birdied five of her first seven holes and carded seven birdies against one bogey.
She tied for 33rd last week at the SBS Open. Last season, Park finished as the low amateur at the Kraft Nabisco Championship, when she tied for 15th.
Prammanasudh, who started on the back nine, birdied four straight holes beginning at No. 4. The Tulane graduate has won once on tour - Franklin American Mortgage Championships in 2005 - and posted six top-10 finishes last year.
Pak, a 23-time winner who is set to be inducted into the LPGA Tour and World Golf Hall of Fame, birdied four holes on the back nine.
Francella, a second-year pro who played just three times last year, posted an eagle, six birdies, a bogey and triple-bogey. Bae also carded an eagle and six birdies and was saddled with four bogeys.
Defending champion Meena Lee of Korea shot a 71 and is tied for 22nd.
With The LPGA Tour finishing up its swing in Hawaii, Annika Sorenstam is waiting until the tour hits Mexico next month to make her season debut.