Mel Reid never won on the LPGA Tour, but is one six-time winner of the Ladies European Tour -12 Reid (Eng); -10 Green (Aus); -9 Yang (Kor), Olson (US); -8 Hall (Eng), Boutier (Fra), Lopez (Mex), Noh (US) Selected others: -5 Ewart Shadoff (Eng); -4 Maguire (Ire); -2 Thomas (Eng)
England's Melissa Reid leads Australian defending champion Hannah Green with two shots entering the final round of the Portland Classic while she seeks her first LPGA Tour title
Reid carded a bogey-free seven-under-par 65 – on her 33rd birthday – to go down to 12 for the tournament.
Green's 68 dropped her 10 under, while England's Georgia Hall is also in battle with 8 under.
"Celebrations will start tomorrow, anyway," said Reid of her birthday.
"I have to behave well tonight and I behaved well last night, which is shocking to many people."
Reid, who finished seventh last week at last week's ANA Inspiration, is a six-time winner of the Ladies European Tour.
"I felt like I really hit it last week [ANA Inspiration] so I took that momentum that kicked in this week," added world number 79.
"I've put myself in a great position, a position that everyone wants to be in, so I'm looking forward to tomorrow's opportunity. I'll just keep doing the same and see where we're going tomorrow afternoon. "
The Columbia Edgewater Country Club tournament has been reduced to 54 holes due to poor air quality due to wildfires in the region.
South Korea's Amy Yang and American Amy Olson are in third place nine below.
Jodi Ewart Shadoff of England is bottom five, with Irish Leona Maguire bottom four alongside Women's Open champion Sophia Popov.