Americans Cristie Kerr, Brittany Lincicome and Lizette Salas shot 3-under 69 on Thursday to share the first-round lead in the U.S. Women's Open.
Ai Miyazato, coming off a victory Sunday in the LPGA Tour event in Arkansas, was a stroke back along with 17-year-old Lexi Thompson, Jennie Lee and Beatriz Recari.
Defending champion So Yeon Ryu opened with a 74 as players struggled in the nearly 100-degree heat and high humidity at Blackwolf Run.
Se Ri Pak, the 1998 Open winner on the course, had a 72.
Top-ranked Yani Tseng shot a 74. She would become the youngest player to complete a career Grand Slam with a victory this weekend.
Second-ranked Stacy Lewis opened with a 77.
Kerr has 14 career LPGA wins and was the 2007 U.S. Women's Open champion.