In the last group of the day, Cristie Kerr and 19-year-old rookie Paula Creamer levelled the entire match with a one-up win over Sweden's Carin Koch and Scot Catriona Matthew.
Cristie Kerr, Brittany Lincicome and Lizette Salas all shot three-under 69 to be a shot clear of teenage compatriot Lexi Thompson, Jennie Lee, Japan's Ai Miyazato and and Spain's Beatriz Recari.