Five-time major champion Yani Tseng seized a one shot lead by firing her second consecutive 68 at the LPGA Tour's Kraft Nabisco Championship.
Taiwan's Tseng is chasing her third-straight LPGA tournament victory and her fourth the last six events.
"You never get tired when you want to win a tournament," Tseng said. "I just figured out I'm tired after the last two wins when you come into this week, but after (Thursday), I had a good sleep, and I relaxed a few days, and I think I'm coming back with a fresh focus."
Tseng, who is trying to become the youngest golfer to win six majors, reached eight-under 136 and has a one shot lead over Haeji Kang heading into the third round of the LPGA Tour's first major of 2012.
Lindsey Wright and Sun Young Yoo were third at six under, while Se Ri Pak was three shots adrift in fifth. Pak shot a 69 to move to five under and is tied with Sweden's Karin Sjodin and world number two Na Yeon Choi of South Korea.
Tseng birdied three of the course's four par-fives and also posted birdies on the fourth and fifth holes.
The 34-year-old Pak had three birdies and a bogey in a five-hole stretch on the front nine. She finished with seven consecutive pars.
Pak has 25 career victories and has won five major championships. She talked about her struggles of late but says she feels she is starting to turn the corner and will be winning again soon.
"I'm having trouble for five or six years, actually," Pak said. "I still love golf, and I can't quit it because I still really want to play.
"It took a lot for myself to be happy. It was difficult to find out. ... Slowly, I know I'm getting better and better, and my attitude and everything is getting slowly better.
"Starting last year around the fall, I don't know how, (but) everything is really calm for me."
Pak has four top-10 finishes in the Kraft Nabisco but is still chasing a win here. She needs to win the Kraft Nabisco to complete the career grand slam.
"This is one of my goals I've set," said Pak. "Getting into the Hall of Fame, that's the biggest, and next, trying to win a major like this. This is the goal for me for 14, 15 years. This is the one I need, but this is the one that always gives me a hard time."