Annika Sorenstam began her bid for a third successive LPGA Championship and the second leg of a possible grand slam with a flawless four-under-par 68 on Thursday.
Sweden's world number one finished one shot off the lead and was safely in the clubhouse when the threat of lightning interrupted play.
Three players finish ahead of her in the second major of the season -- Britain's Laura Davies and two Americans, Laura Diaz and Natalie Gulbis, who was playing with Sorenstam and completed her round with five straight birdies.
America's two precocious golfing teenagers also made their mark.
Paula Creamer, the 18-year-old who won an event in New York last month, joined the four-way tie in joint fourth on 68, while 15-year-old Michelle Wie, the lone amateur in the field, had a 69.
Sorenstam, who has won seven of her last nine tournaments, was delighted with her start.
"It was a very solid round," she told reporters. "I could have played the par fives a little better (she only birdie one of the four) but I also made some crucial par putts and I'm very pleased with my position."
Sorenstam set out from the 10th and her birdies were all from inside 13-feet and came at the long 11th and the par-four 13th, first and fourth.
But perhaps the most important hole was her first, the 373-yard par four 10th.
She pushed her drive into deep rough, pulled her approach left of the green but then made a great up and down, holing from six feet.
Davies, a former world number one and twice former champion, has not won in America for four years. But by finding her form on the greens, the 41-year-old raised hopes of ending a four- year victory drought on the LPGA Tour.
"I've been hitting the ball well all season but holing nothing," she said. "But I've started asking my caddie (Paul Clifford) to read the putts and I managed to hole a few today."
One of the best came at the par five 18th where she rolled one home from 30-feet.
Gulbis, a 22-year-old in her fourth season on Tour, has yet to win, but has shown some fine form this season, including a tie for second at the LPGA Tournament in Williamsburg last month.
Often dubbed the Anna Kournikova of women's golf, the glamorous youngster is based in Las Vegas where she works with Tiger Woods's former coach Butch Harmon.
Wie's only problem was indigestion - and she was delighted when her round was interrupted by a 52-minute weather delay."I feel really stupid," she said. "I ate too much and going out in the heat caused a little indigestion. Everything hurt and if it hadn't been for the siren I think I might have quit."