The 26-year-old had six birdies in her bogey-free round and will head into Sunday's final round two strokes ahead of South Korea's Jiyai Shin after the midway leader carded a 69 in her third round.
Creamer's 16-under 197 total was the lowest 54-hole score in the history of the event, and put her on course for a first victory since the 2010 US Women's Open.
"I haven't won in two years," the nine-time LPGA Tour winner said. "That feels like forever, but it also feels like yesterday when I did just win, so it's kind of a give or take.
"I've been in contention a lot, so it's not that I'm not used to this, that's for sure.
"I feel great. No matter what happens tomorrow [Sunday], I'm just going to go out there and continue what I've been doing this whole year and it's just starting to come together and one round isn't going to make or break it, that's for sure."
Holland's Dewi Claire Schreefel (69) and American teenager Danielle Kang (70) were joint third on 12 under.