WILLIAMSBURG, Virginia, May 4, 2013 (AFP) - Kerr stood on 10-under 203 after 54 holes with compatriot Stacy Lewis and Norway's Suzann Pettersen sharing second on 205, American Angela Stanford on 206 and South Korea's Lee Il-Hee fifth on 207.
Thai teen Ariya Jutanugarn, who led after the first two rounds, stumbled to a 73 on saturday but still shared sixth with American Lizette Salas on 208.
Kerr took her lone bogey at the par-3 second hole but answered with birdies at the par-5 third and par-4 fourth holes. She also birdied the par-5 seventh and began the back nine with another birdie.
Birdies at the par-3 13th and par-5 15th provided Kerr with her margin atop the leaderboard at the end of the day, as well as a boost to the mental game she said is important for her success.
"It goes back to the mental stuff for me," Kerr said. "As long as I take care of the process tomorrow, let the chips fall where they may, take care of the mental stuff, that's my goal."
Kerr said she has produced some of her career best ball-striking this week.
"If I get into my shots, you see the results," she said. "You don't win after three rounds though. I have to get into the flow out there tomorrow and see what happens."
Pettersen will be challenging her after a solid round. She birdied the second hole and added back-to-back birdies at the sixth and seventh before closing the front nine with her only bogey of the day.
The Norwegian ace birdied the 11th and parred the remainder of the back nine, fighting her way through tricky winds.
"It's a ball strikers course," she said. "You have to play smart and find the angles out there. Where the wind is hard I will try to keep the spin under control.
"I'll have to go out tomorrow and be aggressive from the start. I feel sharp. I have to try to just keep the pedal to the metal. My game feels great. I'm in good shape. I feel like I can hit anything that's being asked out there."
It won't be easy. Kerr has nine wins in 21 prior events when leading after 54 holes.
Leading third-round scores on Saturday at the LPGA Kingsmill Championship (USA unless noted, par-71):
203 - Cristie Kerr 66-71-66
205 - Suzann Pettersen (NOR) 68-69-68, Stacy Lewis 68-68-69
206 - Angela Stanford 68-68-70
207 - Lee Il-Hee (KOR) 69-69-69
208 - Lizette Salas 72-71-65, Ariya Jutanugarn (THA) 64-71-73
209 - Park In-Bee (KOR) 68-72-69, Katie Burnett 68-70-71
210 - Mo Martin 68-72-70, Sandra Gal (GER) 68-69-73
211 - Jenny Shin (KOR) 71-72-68, Chella Choi (KOR) 70-73-68, Karrie Webb (AUS) 70-71-70, Caroline Hedwall (SWE) 68-73-70, Irene Cho 70-69-72, Jane Park 68-71-72, Ryu So-Yeon (KOR) 67-71-73, Feng Shanshan (CHN) 69-69-73
212 - Tseng Ya-ni (TPE) 69-72-71, Amy Yang (KOR) 69-72-71, Azahara Munoz (ESP) 68-73-71, Laura Diaz 70-75-67, Giulia Sergas (ITA) 74-68-70, Anna Nordqvist (SWE) 70-72-70, Choi Na-Yeon (KOR) 69-73-70