MOBILE, Alabama, May 18, 2013 (AFP) - Choi, seeking her first LPGA title, stood on 17-under 199 after 54 holes with Nordqvist, who fired a third-round 61, joining second-round leader Jessica Korda of the United States on 200, one stroke ahead of Australian Karrie Webb.
Choi birdied the par-5 fourth, par-4 fifth and par-5 sixth holes for the second day in a row before taking only her second bogey of the event at the par-4 ninth.
She bounced back with another run of three birdies in a row, a string concluded at the par-5 13th, and added another at the par-5 16th to edge ahead of Nordqvist.
Nordqvist, who began the round sharing 27th place, strung together five birdies in a row starting at the par-4 third, taking advantage of both par-5 holes on the front nine in the run.
She began the back nine with back-to-back birdies and added an eagle at the par-5 13th before suffering her first bogey in 30 holes at the par-3 14th.
But Nordqvist responded with three birdies in a row, a run that finished at the par-3 17th, and parred to complete her sensational round.
Korda, out for the past two weeks with a wrist injury, and Hall of Famer Webb each fired 69s.
Korda, whose lone career victory came in the 2012 Women's Australian Open, took a bogey at the par-3 second but answered with a birdie on the next hole and birdied the sixth before closing the front side with back-to-back birdies.
The 20-year-old American stumbled back with a bogey at the 11th and a double bogey at the par-4 12th, although she pulled the strokes back with a birdie at the 13th and an eagle at the 16th.
Webb birdied three of the first six holes before taking her first bogey since the second hole of the first round at the par-4 seventh, but she followed with another birdie at the 16th to stay in the hunt.
American Jennifer Johnson was fifth on 202, one stroke ahead of compatriots Stacy Lewis and Sydnee Michaels with a group on 204 including Americans Nicole Castrale and Lexi Thompson, South Korean Ji Eun-Hee and Thailand's Ariya Jutanugarn.
Leading scores on Saturday after the third round of the Mobile Bay LPGA Classic (USA unless noted, par 72):
199 - Chella Choi (KOR) 67-66-66
200 - Anna Nordqvist (SWE) 73-66-61, Jessica Korda 66-65-69
201 - Karrie Webb (AUS) 69-63-69
202 - Jennifer Johnson 67-70-65
203 - Stacy Lewis 70-70-63, Sydnee Michaels 72-62-69
204 - Ji Eun-Hee (KOR) 65-72-67, Nicole Castrale 67-69-68, Ariya Jutanugarn (THA) 69-66-69, Lexi Thompson 65-70-69
205 - Mariajo Uribe (COL) 70-67-68, Pornanong Phatlum (THA) 69-65-71
206 - Meena Lee (KOR) 70-71-65, Julieta Granada (PAR) 69-70-67, Shin Jiyai (KOR) 72-66-68, Beatriz Recari (ESP) 68-70-68, Park Hee-Young (KOR) 67-71-68, Seo Hee-Kyung (KOR) 68-68-70, Thidapa Suwannapura (THA) 67-67-72
207 - Alison Walshe 69-72-66, Katherine Hull-Kirk (AUS) 69-69-69, Pak Jin-Young (KOR) 70-67-70
208 - Jane Park 73-69-66, Katie Burnett 73-68-67, Lorie Kane (CAN) 72-69-67, Jenny Shin (KOR) 71-70-67, Kim Welch 70-67-71, Lisa McCloskey 69-68-71, Becky Morgan (WAL) 71-65-72, Mina Harigae 67-68-73, Azahara Munoz (ESP) 71-64-73