Each shot a 7-under 64 after Paula Creamer withdrew, taking a one-shot lead over Michelle Wie and Suzann Pettersen after Thursdays opening round at Highland Meadows.
Creamer, who shot a personal-best and course-record 60 in last years first round, withdrew because of a thumb injury moments before her morning tee time.
Pressel was second at the Farr two years ago to five-time winner Se Ri Pak. She didnt have a bogey and birdied four holes in a row late in her round.
Shes won only once since, and is trying to end a victory drought just like her co-leaders.
Kim, who is winless in 56 career LPGA Tour events, twice birdied three consecutive holes during her round. Diaz hasnt won in seven years, but holed a wedge shot for eagle at the par-4 17th hole to move to the top of the leaderboard.
Wie also could use a victory. Despite being in the LPGA spotlight since she was 12, and winning the Womens Amateur Publinx a year later, she is winless since earning her tour card last year. She has three top-10 finishes in her seven starts this season.
She used her length off the tee to shoot her lowest competitive round since turning pro, and rebounded from her only bogey to birdie two of her last three holes. Five of Wies seven birdies came on putts of 10 feet or less.
Pettersen aced the 154-yard third hole with a 7 iron.
Another shot back after rounds of 66 were Cristie Kerr, Inbee Park, Jiyai Shin, Lindsey Wright and Jee Young Lee, as more than half of the field broke par on an overcast day with temperatures in the high 60s.
The large group at 67 was led by top-ranked Lorena Ochoa, making her first appearance at the Farr since 2004. She offset a double-bogey with birdies on her final two holes.
Creamer went wire to wire to beat Nicole Castrale by two shots a year ago.
After an injured left thumb forced her to withdraw from last weeks LPGA stop in Pittsford, N.Y., she saw a doctor Monday in suburban Toledo and received a cortisone shot. She was unable to play a practice round but did participate in the pro-am on Wednesday. Creamer then came to the course Thursday morning and worked on the driving range before tearfully telling tournament officials she was withdrawing.
This is an event I feel a very special bond with and its disappointing not to be able to defend my title, she said in a statement.
Creamer said she hopes to play in next weeks U.S. Womens Open at Saucon Valley Country Club in Bethlehem, Pa.