May Wood stands alone in third place at 4-under-par 68. Joanne Mills, Meredith Duncan and Karin Sjodin are one stroke further back at minus-3 at LPGA International.
The 17-year-old Pressel was denied a petition to play full-time on the LPGA Tour before her 18th birthday, which comes in May. However, she will be allowed to play before then as a sponsor's exemption.
Pressel, who tied for second at the 2004 U.S. Women's Open, birdied five of her last eight holes to climb into a share the lead.
'It could have been better,' Pressel said. 'Hopefully I can continue this. If I can take a little pressure off, it would be nice.'
Despite being only 20-years-old, Miyazato has already won six times on the Japan LPGA Tour. She flew out with four birdies in the first eight holes. Miyazato posted three more birdies to go along with a bogey on the second nine to end at minus-6.
Former Duke standout Brittany Lang, who shared second place with Pressel at the U.S. Women's Open, posted a 2-under-par 70 in round one. She shares seventh place with Becky Iverson, Nicole Jeray, Teresa Lu, Rebecca Coakley, Danielle Downey, Naree Song and Lee Ann Walker-Cooper.
Louise Stahle, who led the Women's British Open after two rounds as an amateur, is one of 15 players at 1-under-par 71.
Among those further down the leaderboard are Kelli Kuehne and Charlotta Sorenstam (plus-3), Jordan Cherebetiu (4-over-par 76), as well as Pearl Sinn-Bonanni and Erica Blasberg (plus-5).
The 90-hole tournament will cut to the low 70 players and ties after the fourth round. Twenty-four players will gain exempt spots on the 2006 LPGA Tour. The next 35 finishers and ties will earn conditional status for 2006.