Mel Reid fired seven birdies in a seven-under par 65 on Saturday to take a two-stroke lead over defending champion Hannah Green in the LPGA Portland Classic.
England's Reid, a six-time winner on the Ladies European Tour who is chasing a first LPGA title, heads into Sunday's final round on 12-under par 132.
"Put myself in great position, a position that everyone wants to be in, so I'm excited for the opportunity tomorrow," said Reid, who strung together four birdies in a row from the sixth through the ninth and rolled in her final birdie of the day at the 18th.
"Just keep doing the same thing and see where tomorrow afternoon takes us," added Reid, who shared seventh at the ANA Inspiration in Rancho Mirage, California, last week.
"I felt like I hit it really good last week, so kind of took that momentum going into this week," said Reid, who said she benefitted from the day off on Thursday after the tournament at Columbia Edgewater was reduced to 54 holes because of poor air quality due to wildfires.
"I think it did me a favor having an extra day off," she said. "I was pretty tired from last week."
Australia's Green, who shared the first-round lead with American Cydney Clanton, followed her opening 66 with a four-under par 68 for a 10-under total of 134.
She shook off a bogey at her opening hole, the 10th and put herself alone in second with a birdie bomb at her final hole, the ninth.
"I got off to such a great start, so it's always hard to back up a low round," said Green, whose two wins last year included her Portland triumph and her first major title at the Women's PGA Championship.
"But I'm really happy with my last putt -- holed a long bomb there so gives me positive momentum for tomorrow."
South Korean Amy Yang and American Amy Olson shared third on nine-under 135.
Yang had seven birdies with one bogey in her six-under 66 while Olson had four birdies without a bogey in her 68.
Clanton tumbled out of contention with a five-over 75 that included five bogeys and a double bogey to go with two birdies.