Feng Shanshan posted a six-under 66 to take a one-shot lead at the U.S. Women's Open as the first round was suspended due to darkness.
Feng holed six birdies at Trump National Golf Club, where inclement weather led to play being suspended for two hours during the afternoon.
The 27-year-old from China, winner of the 2012 PGA Championship, also won bronze at the Rio Olympics last year.
Continuing her bid for a first major title, Amy Yang carded a 67 to be outright second.
Behind Yang - who has finished in the top 10 at majors 16 times - is in a group of three, including star duo Lydia Ko and Ryu So-yeon.
World number one Ryu and the fourth-ranked Ko opened with 68s to be in a tie for third with Carlota Ciganda, who has a hole to play.
While Ryu went through bogey-free, Ko had an up and down round with six birdies and two bogeys.
A group of eight players are tied for sixth at three under, including 15-year-old amateur Rachel Heck and Nelly Korda - who have five holes to play.
Minjee Lee, Lee Jongeun, Choi Hye-jin, Kim Sei-young, Megan Khang and Cristie Kerr completed their three-under 69s.
Danielle Kang, who won the PGA Championship at the start of July, posted a one-over 73.
Defending champion Brittany Lang carded an even-par 72 in the first round.