The Kiwi 17-year-old is now in a share of 12th at five-under, eight shots back from leader Inbee Park (-13). Park is one ahead of Mirim Lee (-12), while Suzann Pettersen is in third at 11-under.
Ko made three birdies and as many bogeys today (sun) after she began her round in a share of fifth place.
This week's tournament will serve as Ko's preparation for next week's major, the LPGA Championship, and she will want a strong finish in her final round tomorrow.
Meanwhile, on the second-tier Web.com Tour, Phoenix-based Kiwi Steven Alker is in a share of 16th at the Price Cutter Charity Championship in Springfield, Missouri.
Alker, who has all but guaranteed himself a spot on next season's PGA Tour, fired a one-under 71 during his third round as he moved to 13-under for the week. The 42-year-old is three shoots off the lead held by Sebastian Cappelen, Martin Piller and Cameron Percy (-16).
There's a logjam of players in second place at 15-under and tomorrow's final round will likely be a close-run thing.
On the PGA Tour China, Kiwi Mathew Perry missed the cut at the Yulongwan Yunnan Open after rounds of 83 and 72.
- by Daniel Richardson of APNZ
