American Stacy Lewis fired a two-under-par 69 to join South Korea's Meena Lee at the top of the leaderboard after the third round of the LPGA North Texas Shootout.
World No 3 Lewis and Lee, who shot a 70 on Saturday, are both on nine-under 204 after 54 holes at the Las Colinas Country Club in Irving.
Norway's Suzann Pettersen, Paraguay's Julieta Granada and American Dori Carter are tied for third, just one shot behind the leading duo after they all carded 68s.
Thailand's Thidapa Suwannapura and South Korean Jenny Shin are in a pack of seven on 206 that also includes Americans Kim Kaufman, Jennifer Johnson, Cristie Kerr, Christina Kim and Natalie Gulbis.
Lewis birdied the par-five seventh but closed the front nine with a bogey.
She rallied with birdies at the 10th and 12th before parring her way back to the clubhouse.
Lee birdied the third and answered a bogey at the fourth hole with back-to-back birdies at the sixth and seventh.
However, a second bogey at the 14th - her only stumble with 10 pars in the last 11 holes - dropped her back into a tie for the lead with Lewis.
World No 1 Inbee Park of South Korea, who is the defending champion, shot a 68 and is only three strokes off the lead, while American duo Lexi Thompson and Michelle Wie are one shot further back.