Suzann Pettersen and Na Yeon Choi pushed each other to the top of the leaderboard in perfect morning conditions in the Kraft Nabisco Championship.Jodi Ewart Shadoff matched them late Thursday afternoon with a scrambling par on the par-5 18th after her drive went to the right and found the deep rough behind a tall tree."There were two options," said Ewart Shadoff, the 25-year-old Englishwoman in her second full year on the LPGA Tour. "Punch fade it around the tree, left, or punch it right around the tree and keep it over the bunker at the same time. I took the safer route and it paid off."It left her with a 187-yard shot into the wind to the water-guarded green. While most players hit wedges on their third shots on the hole, she had to use a 3-wood."The wind picked up," she said.Her shot settled on the back right of the green, and the newlywed lagged her 30-footer to tap-in range to tie Pettersen and Choi at 4-under 68 at Mission Hills."I've been playing really consistently the last three or four tournaments, so I knew, my game is right there and I knew I was due to have a really good round," Ewart Shadoff said.Playing in the last group of the day off the first tee, the former New Mexico State player made four straight birdies - the last with a 20-foot putt on the par-3 14th - to take the lead at 5 under, but missed a 4-foot par putt on the par-4 16th to drop back."I played really consistently and got on a birdie train in the middle of my round," Ewart Shadoff said. "I was hitting a lot of greens and making a lot of putts."Pettersen and Choi made it look easy in the morning, finishing well before the wind picked up and the temperature climbed into the low 90s in the Coachella Valley."The course is perfect," Pettersen said. "Greens are rolling pure. If you miss the fairways, you can be in a bit of trouble. The rough is deep. I missed one or two."Pettersen birdied the final three holes on her front nine and got to 4 under with a birdie on the par-4 seventh, her 16th hole. The Norwegian, a 10-time LPGA Tour winner ranked eighth in the world, had consecutive victories late last season in South Korea and Taiwan and won a European tour event last month in China."Today was everything I could ask for in the opening round," Pettersen 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."The third-ranked Choi fed off the pairing with Pettersen."I think I played well because she played well, too," said Choi, the South Korean player who won the U.S. Women's Open and the Titleholders last year. "We motivated each other."Choi made a 30-foot birdie putt on the 14, matched Pettersen's birdies on Nos. 16 and 17 and grabbed a share of the lead with a 12-foot birdie putt on the par-5 ninth."She's a strong competitor, but I tried to chase her until the last hole," Choi said.Anna Nordqvist and Amy Yang were a stroke back at 69.Nordqvist is trying to regain the form she showed as a rookie in 2009 when she won the LPGA Championship and LPGA Tour Championship."Most of all, it just feels good that pieces of the puzzle are coming together and things I'm working on are paying off," Nordqvist said. "I'm very happy about that."Top-ranked Stacy Lewis had a 73. She made a triple-bogey 6 on No. 14, three-putting after her tee shot trickled into the water."I'm definitely disappointed, but I made some putts there on the back nine," Lewis said. "I just kind of had to fight through it a little bit today."Lewis won the 2011 tournament for her first LPGA Tour title. She won four times last season to take the player of the year award and added consecutive titles this year in Singapore and Phoenix."This course, you're never really out of it," Lewis said. "You can shoot a good number one day and be right there."Michelle Wie and 15-year-old amateur Lydia Ko each shot 72 in their morning pairing."It was fun," Ko said. "She's my idol."Ko won the Canadian Women's Open last August to become the youngest LPGA Tour winner. The South Korea-born New Zealander has two other victories in pro events, winning the New South Wales Open last year and the New Zealand Women's Open this year."It was a pretty solid start," said Ko, also the U.S. Women's Amateur winner last summer. "My putts didn't fall, but I felt like I rolled it really well."Playing the back nine first, Wie was 2 under through 13 holes, then dropped back with two bogeys."It was a shame," Wie said. "Unfortunately, made two really stupid mistakes."In five events this year, Wie has missed three cuts and also struggled in two no-cut events in Asia. She has broken 70 only once in 15 rounds this season."It feels good to show that I could have shot 66 out here, and it feels good that I know I left a lot of birdie chances out there," Wie said. "I'm just excited for tomorrow. Just can't wait to go out there and make some birdies."Yani Tseng, playing for the first time since losing the No. 1 ranking to Lewis in Phoenix, also opened with a 72. The 2010 winner at Mission Hills, Tseng was booted out of the Kia Classic two weeks ago when she overslept and missed her pro-am tee time."Today it seemed like I was trying too hard," said Tseng, winless in more than a year. "There's three more days to come and I know I can shoot a low score."Defending champion Sun Young Yoo had a 77. She beat I.K. Kim with a birdie on the first playoff hole last year after Kim missed a 1-foot putt on the final hole of regulation. Kim also struggled, shooting 75.