RANCHO MIRAGE - Na Yeon Choi, Suzann Pettersen and Jodi Ewart Shadoff fired four-under par 68s Thursday to share the first round lead at the LPGA Kraft Nabisco, the first major of the season.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."I've been playing really consistently the last three or four tournaments," Ewart Shadoff said. "And so I knew my game is right there, and I knew I was due to have a really good round." Choi, ranked third in the world, teed off on 10 and picked up her first birdie at the 14th, draining a 30-footer from the fringe.A brace of birdies at 16 and 17 was followed by nine pars before she punctuated her round with a birdie at the par-five ninth. "I'm really happy I played without a bogey today, but luckily I played in the morning today and the greens and fairways are a little softer than the afternoon," she said.Pettersen also started on the back nine and came alive with three birdies in a row from the 16th. Her only other birdie came at the par-four-seventh. "Today was everything I could ask for an opening round," the Norwegian said. "Just feeling really good all week, and it's just about kind of trusting what you have, and I couldn't ask for a better start."Pettersen has three runner-up finishes in this event. Despite her desire to go one step better, the fiercely competitive player believes it's important to enjoy the experience. "You know what, it's really just try and go out there and literally try to enjoy it, which is probably the hardest thing for me," she said.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. Tseng can reclaim the world No. 1 ranking from Lewis with a victory this week.