Yani Tseng of Taiwan was frustrated by a pair of short misses yet emerged with a one-stroke lead on Friday after the second round of the LPGA Championship, the second women's major of the year.
World number one Tseng followed her opening-round 66 with a two-under-par 70 for an eight-under total of 136 on a day of off-and-on rain at Locust Hill Country Club outside Rochester.
"I feel a little disappointed about my round," Tseng told reporters. "I missed two short putts today. I probably tried too hard and thought too much today. Just overthinking."
In second place was American Pat Hurst, 42, who surged up the leaderboard with a five-under-par 67 for 137 in her quest to add another major crown to her 1998 triumph at the Nabisco.
Another shot back were American Morgan Pressel, Minea Blomqvist of Finland and South Korean Park Hee-young, who each posted a second successive 69s for six-under totals of 138.
Americans Paula Creamer (72) and Cindy LaCrosse (69), and Amy Yang of South Korea were tied on five under par.
Tseng, who started her round on the 10th in the afternoon wave, lost her lead temporarily to morning starter Hurst before running off a string of three birdies from her fourth hole on to reach nine under par.
However, the 22-year-old Taiwanese lost her way from the tee on the next few holes and gave back two strokes with a double-bogey six at 18, where she missed a putt of 18 inches.
She rebounded by sinking a 20-foot birdie putt right after making the turn.
After taking another bogey, her other botched putt came at the par-five eighth hole where she missed a three-footer for eagle but still made a birdie to move into the lead.
"I'm still very excited," said Tseng, who is gunning to become the youngest golfer to collect four major crowns.
Hurst, whose last of six career LPGA wins came two years ago in Mexico, said she had regained her enthusiasm for golf.
"I'm playing good. I'm hitting the ball well. And if I could get some putts falling and getting some confidence back, I'll feel good about my game," said Hurst.
Pressel was upbeat about her chances despite making three bogeys following a bogey-free tour of Locust Hill on Thursday.
"I felt good out there," Pressel said. "Today I had more birdies, six birdies. I can take that momentum going into tomorrow."