Eun-Hee Ji fired a three-under 69 on Saturday to take a one-shot lead over Karrie Webb after three rounds of the LPGA Championship, the tour's second major of the season.
Ji moved to four-under-par 212 during a day when rain delayed play at Locust Hill Country Club for more than two hours.
But Ji managed a very good score and will carry a slight advantage into the final round, when she will try for her second major title. The 26-year-old won the U.S. Women's Open in 2009.
Webb, a seven-time major champion and 2001 LPGA Championship winner, shot a four-under 68 to move into second place at minus-three.
World No. 3 Stacy Lewis climbed into contention with a two-under 70. The American has already taken two victories this year to add to her title at last year's Kraft Nabisco victory.
Lewis sits at two-under 214 and shares third with world No. 5 Suzann Pettersen (71), Inbee Park (72) and first-round co-leader Giulia Sergas. The Italian Sergas fell behind thanks to a 76 on Friday, but rebounded with a third-round 69.
Second-round leader Se Ri Pak, playing for the first time since she dislocated her shoulder in early April, struggled on Saturday. The Hall of Famer carded a four-over 76 and tumbled down the leaderboard into a share of 15th, at plus- one.
Webb played in a threesome that started about an hour before the leaders, starting on the first tee, and didn't get off on the right foot. She bogeyed the first to fall to plus-two, then parred the next six holes.
But Webb started making up strokes at the par-five eighth, which she birdied. She added another at 10, then made two in a row from the 14th. Another birdie at the 17th pushed her score to minus-three.
As Webb made her run, the leaderboard was changing around her. Multiple players got close to first only to lose the ground, including 2010 U.S. Women's Open winner Paula Creamer.
Creamer birdied two of her first holes and was in the mix for most of the round. Even after bogeying the 13th hole, she still sat amongst the leaders at minus-three.
But Creamer couldn't stay in that group. She bogeyed 16 and 18 and fell into a group of seven tied for seventh at one-under.
Creamer was joined there by another American, Jennifer Johnson, who endured a more drastic score change. She eagled the 17th to reach minus-three, but double-bogeyed the last.
Ji, playing in the same threesome as Creamer, managed to avoid similar problems. After a bogey at four put her at minus-one, the South Korean followed with back-to-back birdies.
She then birdied 11 and 15 to build a two-stroke edge, but a bogey at 16 brought her back toward the field. However, she managed to par the final two holes to maintain her lead.
"Today my iron shots help with play. I keep the fairway, and I'm hitting really close to the hole and I make easier putts," Ji said.
Ji previously won at Locust Hill in 2008 at the Wegmans LPGA, an event that stopped being run in '09 and was replaced by the LPGA Championship the following year.
Four years removed from that victory and back on the same course, Ji is chasing another title.
Her Sunday playing partner, Webb, has put together one of the best careers in the history of women's golf. The Hall of Famer has more LPGA victories (38) than any other active player, though hasn't won since last March and hasn't finished first at a major since the 2006 Kraft Nabisco.
"Whether I win tomorrow or not, just the feelings that I will have tomorrow with a chance to win is what I work hard for," Webb said. "And I probably want it more now than I ever have in my career just because I don't feel it as often as I would like."
Another shot behind is the third-place group. Lewis had a relatively problem- free round, with three birdies and one bogey, but the others weren't so fortunate.
Sergas had six birdies and three bogeys, including one at the last, while Pettersen needed to overcome a double-bogey at the second hole. Park stumbled to two late bogeys, and only got to two-under thanks to a birdie at 17.
But Park is still very much in contention. While Ji is alone in the lead, she said her one-stroke advantage made her a "little bit nervous."
And the way this tournament has been going, Ji's lead is by no means safe. Webb said she expects the leaderboard to be very bunched Sunday, and that "it's not just the people in the lead that have a chance to win."
NOTES: Jodi Ewart shot a 72 that included a hole-in-one at 15 and an eagle at 17. She is tied for 25th at plus-three...World No. 1 and defending champion Yani Tseng carded a two-over 74. She sits at plus-nine, tied for 59th.