Kemp is tied for fourth at 12 under, four shots behind leader Ally Ewing in the Kroger Queen City Championship.
The American shot into the lead with a fast start and stayed there on a soggy course on Saturday - her five-under 67 building a one-shot lead over Mexican Maria Fassi (67) who's aiming for her first LPGA title.
Ewing's first order of business this deep in the season is to make sure she is among the 60 who reach the final event, which she has done every year since 2017. A victory would take care of that.
Ewing has not finished in the top 10 all year, but she was practically flawless at Kenwood Country Club. She had six birdies and was bogey-free until the final hole.
China's Xiyu Lin (70) is third at 14 under while Megan Khang (69), Thailand's Ariya Jutanugarn (69) and 36-hole leader Jeongeun Lee6 (73) of South Korea join Kemp two strokes further back.
American Khang and Kemp are trying to win on the LPGA Tour for the first time.
"We saw last week Gaby (Lopez) and I kind of fought it out in our group, and I think we were like third or fourth to last group. So it's golf. Anything can happen," Khang said.
"Just got to stay within yourself and give yourself the chance."
Ewing, with two LPGA victories in her career, started the third round one shot behind and quickly erased that with a pair of birdies, along with another on the par-5 fourth hole.
The 29-year-old, who has won in each of the last two years on the LPGA tour, birdied all four of the par 5s.
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