RANCHO MIRAGE, California, April 4, 2013 (AFP) - Both South Korea's Choi and Norway's Pettersen had four birdies with no bogeys on the par-72 Dinah Shore tournament course at Mission Hills, while England's Ewart Shadoff had six birdies and two bogeys.
Ewart Shadoff had seized the outright lead with four holes to play thanks to a four-birdie burst starting at the par-five 11th, but she gave back a stroke with her second bogey of the day at the 16th.
The leading trio was one stroke in front of South Korean Amy Yang and Sweden's Anna Nordqvist.
World No. 4 Inbee Park was among 11 players who shot 70, including her South Korean compatriots Jiyai Shin and Hee Young Park, Italy's Giulia Sergas and Thailand's Moriya Jutanugarn.
American Stacy Lewis, playing her first major championship since toppling Taiwan's Yani Tseng from the top of the world rankings, settled for a one-over par 73 that included a triple-bogey six at the par-three 14th.
Tseng was among a big group on even-par 72 which also included Hall of Famers Karrie Webb of Australia and Se Ri Pak of South Korea -- along with New Zealand teen prodigy Lydia Ko.
Leading first-round scores here on Thursday in the $2 million LPGA Kraft Nabisco Championship (USA unless noted; a denotes amateur, par-72):
68 - Jodi Ewart Shadoff (ENG), Na Yeon Choi (KOR), Suzann Pettersen (NOR)
69 - Amy Yang (KOR), Anna Nordqvist (SWE)
70 - Jane Park, Jacqui Concolino, Moriya Jutanugarn (THA), Jiyai Shin (KOR), Angela Stanford, Giulia Sergas (ITA), Hee Young Park (KOR), Jessica Korda, Inbee Park (KOR), Lizette Salas, Caroline Masson (GER)
71 - Alison Walshe, Pornanong Phatlum (THA), Louise Friberg (SWE), Caroline Hedwall (SWE), a-Ashlan Ramsey, Cristie Kerr
72 - Haeji Kang (KOR), Yani Tseng (TPE), Karrie Webb (AUS), Hee Kyung Seo (KOR), Morgan Pressel, Mina Harigae, Sarah Jane Smith (AUS), Mariajo Uribe (COL), Karin Sjodin (SWE), a-Lydia Ko (NZL), Michelle Wie, Catriona Matthew (SCO), Karine Icher (FRA), Se Ri Pak (KOR), Jennifer Johnson, Cindy LaCrosse, a-Camilla Hedberg (ESP), Pernilla Lindberg (SWE), Dewi Claire Schreefel (NED), Paige MacKenzie, Ayako Uehara (JPN)