Ko only shot one bogey in her third round on Saturday but two birdies on the 12th and 15th holes weren't enough to make headway. Her biggest struggle came off the tee, hitting only seven of 14 fairways, with a poor average driving distance of just 215 yards.
Despite those issues, Ko still hit 12 greens in regulation, and was saved by a decent day with the putter, needing just 26 putts to complete her round.
Without a win in 15 months, Ko has recorded three top-three finishes in her last five tournaments, and can keep alive a five-tournament streak of making the top 25 with another solid round tomorrow afternoon.
American leader Cristie Kerr started slowly but has charged into the lead with rounds of 63 and 65 to be 15-under, one stroke ahead of China's Shanshan Feng.
Elsewhere, the Kiwi duo of Ryan Fox and Michael Hendry are well off the pace at the World Golf Championship event in China.
Hendry carded a one-under 71 to move up to a tie for 52nd at three-over, while Fox shot a three-over 75 to tumble back to a share of 33rd at one-under for the tournament.
The event is led by a dominant Dustin Johnson at 17-under, who followed up his second round 63 with a penultimate round of 68. For the second day in a row, Johnson had one of the lowest rounds of the day, with his four-under effort the second-best on the course in tougher conditions.
Johnson leads by six shots over fellow American Brooks Koepka, with Sweden's Henrik Stenson in third at 10-under.
