Jodi Ewart caused an upset in the first round of the Sybase Match Play Championship as she knocked out defending champion Suzann Pettersen.
England's Ewart, ranked 210th in the world, found herself two down after two holes, but was back on terms with the world No.3 after the fifth.
The 24-year-old took the lead at the 12th in New Jersey and never gave it up from there as she claimed a 3&1 victory.
Ewart told lpga.com: "I wanted to get off to a really good start and that didn't really happen that well.
"After two I was like, I am going to get absolutely thrashed.
"So then when we both parred number three, it just really calmed me down."
She added: "On paper I'm not supposed to win at all, so there's no pressure on me.
"I just went out there and played really fearless golf because I was attacking pins."
World No.1 Yani Tseng battled into the second round with a one-up victory over Jeong Jang.
Tseng was four up through six against Jeong Jang, but after 15 it was all square once again.
Tseng then took control again with a par at the 16th, before splitting the last two holes to advance.
Ewart was the only Briton to advance as Catriona Matthew was upset 3&1 by Candie Kung, while Karen Stupples lost 4&3 to Sophie Gustafson. Sweden's Gustafson is next up for Ewart.
Other notable players to fall included Ai Miyazato, Paul Creamer and Brittany Lincicome.
Collated first-round scores, Hamilton Farm Golf Club, Gladstone, New Jersey, United States of America
(USA unless stated):
Anna Nordqvist (Swe) bt Beatriz Recari (Spa) 2 & 1
Jiyai Shin (Kor) bt Jennifer Song 6 & 5
Mika Miyazato (Jpn) Lost to Natalie Gulbis 1 down
Amy Yang (Kor) bt Amy Hung (Tai) 3 & 2
Inbee Park (Kor) bt Hee-Won Han (Kor) 3 & 2
Morgan Pressel bt Mindy Kim (Kor) 5 & 4
Jenny Shin bt Jimin Kang (Kor) 4 & 2
Na Yeon Choi (Kor) bt Grace Park (Kor) 2 up
Hee Kyung Seo (Kor) Lost to Jessica Korda 1 down
Sun Young Yoo (Kor) bt Amanda Blumenherst 4 & 2
Sandra Gal (Ger) bt Pornanong Phatlum (Tha) 2 up
Stacy Lewis bt Pat Hurst 4 & 3
Azahara Munoz (Spa) bt Lindsey Wright (Aus) 4 & 3
Karrie Webb (Aus) bt Tiffany Joh 4 & 3
Sophie Gustafson (Swe) bt Karen Stupples (Eng) 4 & 3
Suzann Pettersen (Nor) Lost to Jodi Ewart (Eng) 3 & 1
Caroline Hedwall (Swe) Lost to Haeji Kang (Kor) 3 & 2
Catriona Matthew (Sco) Lost to Candie Kung (Tai) 3 & 1
Chella Choi (Kor) Lost to Katie Futcher 4 & 3
Yani Tseng (Tai) bt Jeong Jang (Kor) 1 up
Maria Hjorth (Swe) Lost to Eun Hee Ji (Kor) 1 down
Angela Stanford bt Wendy Ward 2 & 1
Meena Lee (Kor) Lost to Vicky Hurst 2 & 1
Cristie Kerr bt Belen Mozo (Spa) 2 & 1
Hee Young Park (Kor) Lost to Karine Icher (Fra) 4 & 2
Paula Creamer Lost to Jennifer Johnson 2 & 1
Brittany Lang Lost to Julieta Granada (Par) 2 & 1
Brittany Lincicome Lost to Ryann O'toole 2 & 1
Michelle Wie Lost to Mina Harigae 3 & 2
So yeon Ryu (Kor) bt Karin Sjodin (Swe) 2 & 1
Song-Hee Kim (Kor) Lost to Katherine Hull (Aus) 3 & 2
Ai Miyazato (Jpn) Lost to Mariajo Uribe (Col) 2 down