The top two seeds in the LPGA Tour event met in the finals last season and were favored to return to the title match this year. But they lost to a pair of unheralded players from the Japanese LPGA Tour.
Sorenstam, the defending champion who was seeking her 10th LPGA title of the season, fell to Chieko Amanuma, 2 & 1. Pak, who is second on the tour with five wins this year, lost to Takayo Bandoh, 1-up.
On the verge of her fifth LPGA Tour Player of the Year honor, Sorenstam had three events left to become the first golfer since Kathy Whitworth and Carol Mann in 1968 to win 10 times in one year. But Sorenstam never got her putting going and was two back with two to play before halving the 17th.
"I just didn't make anything," Sorenstam said. "You've got to make birdies in match play, and I just didn't make them. (Amanuma) played very steady and once she got going, she played better and better."
Pak had kept the Swedish star from her place in history at the past two LPGA Tour stops, winning both. Last week in her native South Korea, she won the CJ Nine Bridges Classic by six shots.
But her putting also let her down as she settled for two birdies to go with one bogey, which resulted in her tight match with Bandoh. Pak was also 2-down with two to play and won the 17th to keep the match going before halving the final hole.
"She played well," Pak said. "Match play is different and 18 holes is so short. She just made a lot of putts. I did my best. I missed a lot of putts and was just unlucky. The grass is a different speed on the greens and different grass in the fairways. She made a lot of unbelievable putts."
The third seed from the LPGA also lost as Mi Hyun Kim was beaten by Midori Yoneyama, the 14th seed from the Japanese LPGA, 1-up.
That leaves Karrie Webb as the likely favorite, although she has won just twice this year. Webb, the LPGA's fourth seed, advanced to the second round with a 3 & 2 victory over Hsiu-Feng Tseng.
"I'm not surprised because I knew before playing this week how good of a standard of play there is on the JLPGA," Webb said regarding the upsets. "The 16th-seeded JLPGA player can certainly beat the top player seeded on the LPGA side. Week in and week out, Annika is going to be the best player in the world, but in match play for only 18 holes, anyone can win."
Webb endured an up-and-down day in which she lost the first two holes before winning the next three to take the lead, and was steady the rest of the way. She next faces Grace Park, who defeated Japanese LPGA fifth seed Mikino Kubo, 4 & 3.
Rosie Jones posted a 5 & 4 victory over Mihoko Takahashi and Lorie Kane, a semifinalist here last season, cruised to a 7 & 6 thrashing of Orie Fujino.
LPGA tour members posted an 11-4 record in the first round. Amanuma, Bandoh, Yoneyama and Yuri Fedoh were the winners from the Japanese tour.
The match between Rachel Teske and Yu-Chen Huang was all square through 27 holes before being suspended due to darkness.