Britain's Laura Davies reached the turn in two under par 34 - but it was the irrepressible Karrie Webb that set the pace in the first round of the Nabisco Championship at Palm Springs in California.
The world number one, whose record this year is four wins and a second place, shot a five under par 67 to lead the first Major by two shots from fellow Australian Rachel Hetherington.
But on a course playing long and tough, Davies was also one of the few to move into the red figures.
The Briton is desperate to win the title to complete the Grand Slam of four women's Majors, and birdies at the seventh and long ninth saw her reach the turn in two under.
Webb, who won the last Major, the du Maurier Classic, last August, produced a flawless performance.
She birdied the fifth and seventh to be out in 34 and then made more gains at the 10th, 11th and 16th.
But it was a disappointing opening day for the Swedish Sorenstam sisters. Charlotta, who won her first event in Phoenix last Sunday, had a 75, while Annika - the winner in Tucson two weeks ago - stumbled to the turn in 40 and eventually posted a disappointing 76.
67 K Webb (Aus) 69 R Hetherington (Aus) 70 B Daniel 72 M Hjorth (Swe) 73 W Doolan (Aus), M Zimmerman, L Lindley, A Okamoto (Jpn) 74 C Flom, T Green, J Geddes, M McGann, B King 75 P Hammel, C McCurdy, B Iverson, P Sinn, C Sorenstam (Swe) 76 J Kang (amateur), A Alcott, D Richard, M Lunn (Aus), A Sorenstam (Swe)