Former world number one Tseng Ya-ni fired an eight-under par 64 on Friday to grab a one-stroke lead in the weather-hit second round of the LPGA Classic.
Taiwan`s Tseng notched six birdies and an eagle en route to a 10-under par total of 134, one stroke in front of American Austin Ernst who carded a 65 for 135.
American Lexi Thompson was in the clubhouse on eight-under 136 after posting a 67, with both Paraguay`s Julieta Granada and American Sydnee Michaels at eight-under on the course when darkness halted play.
Tseng wasn`t affected by the thunderstorm that held up play for more than an hour and a half on Friday evening.
As playing partner Stacy Lewis put it, Tseng looked like the "old Ya-ni" as she piled up birdies on the Senator course.
Currently ranked 75th in the world, Tseng dropped out of the top spot in the rankings in 2013 and hasn`t won an LPGA title since 2012.
Tseng has showed signs of returning to form in recent weeks, with three top-22 finishes in her last four starts.
The last time Tseng held the 36-hole lead was at the 2012 Kraft Nabisco Championship, where she finished third.
"Just very happy my game`s really coming back," Tseng said. "I`m really happy playing golf on the course and I want to win.
"But it doesn`t matter, it will come. It doesn`t matter if it`s this week or next week or next year, (I) just try to be patient as much as I can and stay positive."
Ernst`s roller-coaster day included eight birdies, three bogeys and an eagle.
She and playing partner Thompson combined for 13 birdies in the round.
"We both had a string of birdies there on the front nine. She was hitting it well," Ernst said. "Definitely when you see putts going in with other people, too, I think it just kind of gives you a little bit more confidence that you can just take it deep."
Thompson held or shared the lead with Ernst for much of the day, finishing without a bogey on the course where she claimed her first LPGA tour title in 2011.
"It helps knowing the golf course really well," said Thompson, who was runner-up here in 2012. "It`s probably in the best shape I`ve seen it, especially the greens are rolling really well.