World No. 1 Yani Tseng of Taiwan closed with an eagle to fire a five-under par 66 and grab a share of the lead after Friday's first round of the 54-hole LPGA Northwest Arkansas Championship.
Defending champion Tseng, seeking her eighth worldwide triumph of the year and 10th career LPGA victory in the $2 million event, was level atop the field with local heroine Stacy Lewis, who birdied three of the last four holes.
"I just focus on every shot," Tseng said. "I don't feel like I need to win this because I won last year. Every year is different. All the great players improve from the last year, so you never know."
"All you can do is do your best, have a good attitude and then enjoy."
At 22, Tseng became the youngest golfer, man or woman, to win a fifth career major title by capturing last month's Women's British Open. She leads the LPGA money list, Player of Year race and owns the LPGA low season scoring average.
Tseng's bogey-free round at Pinnacle Country Club included birdies at the par-5 seventh and par-4 eighth and another birdie at the par-5 14th.
Lewis, who attended the nearby University of Arkansas, birdied the par-3 sixth and began the back nine with another. She birdied the par-3 15th and 17th holes and closed with a birdie at the par-5 18th to match Tseng at the top.
Lewis, who won her first title in April at a major, the Kraft Nabisco, said winning in Arkansas would be as big as winning a major title.
"For me this golf tournament is another major," Lewis said. "It would be up there with the Kraft to win it. It would be awesome. It would be one of those wins that I would never forget probably."
Britain's Karen Stupples, South Korean Jim Young Pak and American Taylor Leon, seeking her first LPGA triumph, shared third on 67.
Stupples, whose two career titles came in 2004, birdied the par-5 second and seventh holes around a birdie at the par-4 fourth and she added a birdie at the par-3 15th to grab a share of second.
Leon's bogey-free round began with back-to-back birdies. She added another birdie at the par-4 12th hole, and her last at the 14th hole to finish on 67.
Leon posted the best finish of her four-year LPGA career at this event two years ago with a share of sixth. She has missed the cut in four of her eight events this season and cracked the top 60 only once.
Pak, who began on the back nine, took a bogey at the par-3 11th hole but birdied the par-3 17th. After another bogey at the par-3 third she birdied the next five holes and closed with a par to stand one stroke adrift of the leaders.
Norway's World No. 2 Suzann Pettersen closed with a bogey to fall into a pack on 68.
Pettersen birdied the fourth and added back-to-back birdies at the par-5 seventh and par-4 eighth. After starting the back nine with a bogey, she responded with birdies at the par-4 12th and par-5 14th holes.
Pettersen won last month in Portland, Oregon, and captured the LPGA Match-Play crown in May, making this her best season since she captured five of her eight career LPGA titles in 2007.