The world number four made the most of a calm morning in the California desert, recording five birdies on the way to a flawless five-under-par 67 on the 6,702-yard layout at Mission Hills Country Club.

Driving the ball superbly on one of the LPGA Tour's longest courses, the blonde Pettersen surged to the top of the first-round leaderboard in the opening women's major of the year.

Twice champion Karrie Webb of Australia carded a 69 to finish level with South Koreans Min Na-on and Kim Song-hee, Britain's Becky Brewerton and American Vicky Hurst.

World number one Lorena Ochoa of Mexico, winner here in 2008, and fan favorite Michelle Wie of the United States were among the late starters.

"It was a very good, solid round of golf and I could not ask for a better start," Pettersen, 28, told reporters after covering her last nine holes in two-under 34.

"I had a few good bounces out there but I am feeling very good with my driver which helps around this place. Plus I am making a few putts so it was very stress-free golf today."

A top-five finisher here for the last three years, the Norwegian was delighted to be back in competition following her withdrawal from last month's ANZ Ladies Masters.

"I'm pain-free now so that's the most important thing," said Pettersen, who pulled out on the eve of the Ladies European Tour-sanctioned event due to pain in her left hip.

"It was a little flare on the bone. They thought it was bursitis because the symptoms were very, very similar. I got it checked out and they didn't really find much.

"I got a cortisone shot and that helped a little bit. It healed just in time to come here. Now I'm starting to feel really good about how my game is looking and feeling." Although the final nine holes of Pettersen's round unfolded under blue skies in dazzling desert sunshine, she had teed off in surprisingly bleak conditions.

"It got really cold as we warmed up and I thought I was going to ski, the way I was dressed," she joked. "But once the sun came out it was beautiful and the wind stayed down.

"This course is in such very, very good shape so it's a pleasure to be out there."