The third-ranked Pettersen was eliminated 3 and 1 by relative unknown Jodi Ewart of England on Thursday in the first round of the LPGA Tour event, while Paula Creamer, Brittany Lincicome and Michelle Wie lost to some equally obscure fellow Americans.

Creamer, the No. 8 seed, was beaten 2 and 1 by Jennifer Johnson, the No. 57 seed. No. 9 seed Lincicome was ousted 2 and 1 by No. 56 Ryann O'Toole. The 20th-seeded Wie was knocked out by No. 45 Mina Harigae, 3 and 2.

Yani Tseng, Na Yeon Choi and Cristie Kerr, the world's Nos. 1, 2 and 5 players, barely advanced to the second round, while the day ended with No. 4 ranked Ai Miyazato of Japan being surprised 2-up by Mariajo Uribe of Colombia in the final match at Hamilton Farm Golf Club.

"It's not an easy course to play," said Tseng, who escaped with a 1-up win after Jeong Jang missed a 6-foot birdie attempt to force a playoff. "This is the top 64, that's why we play here. So I mean, you cannot expect the first one is going to be easy to win."

However, it was still surprising to see the field lose a ton of its star attractions, with the biggest surprise being the loss of Petterson to Ewart, who is ranked No. 202 in the world and 62nd in the event.

What made the exit even more surprising was Pettersen, still looking for her first win of the season, won the first two holes to go 2-up.

Ewart even had doubts after her shaky start.

"After No. 2 I was like, I am going to get absolutely thrashed," Ewart said.

Ewart calmed down after making a par at the third hole and then made a long birdie putt at the next hole after getting a read off Pettersen's birdie attempt. A 7-footer for birdie tied the match at the fifth hole and it was game on.

Ewart took the lead for good at No. 12 when Pettersen conceded the hole and followed that with a tap-in birdie at No. 13. Pettersen won the 14th when Ewart three-putted, but the 24-year-old made a 10-footer at No. 15 to halve the hole and restored her 2-up lead with a short birdie at No. 16. She closed out the match at No. 17 when Pettersen conceded after missing a birdie putt.

"On paper, I'm not supposed to win at all, so there's no pressure on me," said Ewart, a former University of New Mexico player whose best finish this year was a tie for seventh in the Kia Classic. "I just went out there and played fearless golf because I was attacking the pins."

Pettersen, from Norway, refused to comment after her match.

Creamer never led in her match against the 20-year-old Johnson, who is in her second year on tour. Creamer was 3-down after five holes, but twice managed the get back all square. She fell behind for good with a bogey at No. 14 and another one at No. 17 ended the match.

Lincicome, who will defend her title in the ShopRite Classic near Atlantic City in two weeks, also never led against O'Toole, a former UCLA player who also is in her second year on tour. This marked the second straight year Lincicome has been eliminated in the first round.

Wie also played from behind against the 22-year-old Harigae. The former Duke player took the lead for good with a birdie at No. 8.

Choi was all square with fellow South Korean Grace Park after 16 holes, but she birdied the final two for a 2-up win.

"It was a tough game," said Choi, who lost in the semifinals last year.

Uribe won four of the last five holes to eliminate Miyazato.

Natalie Gulbis staged the best comeback of the day, rallying from 4-down with eight holes to play to stun Mika Miyazato — no relation to Ai. Gulbis made a 5-foot birdie putt at No. 18 to advance.

Kerr, who lost in the final to Pettersen last year, broke a tie with birdies at the 13th and 14th holes en route to a 2-and-1 win over Belen Mozo of Spain.

"You've got to win or you go home," Kerr said. "She gave me a really good match. She made a lot of clutch par putts, and I let her off the hook a little bit three-putting 10," Kerr said. "It was a hard-fought battle on both parts."

 By TOM CANAVAN, AP Sports Writer