Venezuelan rookie Veronica Felibert fired a five-under 66 to stretch her lead to four shots heading into the final round of the LPGA Tour's NW Arkansas Classic.
Felibert, who celebrated her 27th birthday Saturday, continued her surprising run which saw her shoot an opening round 65 to take a one-stroke lead.
She got into the tournament as a second alternate after missing the cut in her three previous events.
Felibert is in her first year on the LPGA Tour. She finished two rounds at 11-under-par as she set a tournament 36-hole record with her 131 total.
The previous record of 132 was set by Meena Lee and Ji Eun-hee in 2008, then equalled by Michelle Wie in 2010.
Japan's Mika Miyazato and South Korea's Park In-bee were tied for second at the Pinnacle Country Club course. Miyazato had a 65, and former US Women's Open winner Park shot a three-under 68.
Felibert, who is ranked 723rd in the world, shot a bogey-free round Saturday, closing her round with a par-saving putt on the final hole.
"There are feelings that I cannot express right now, because it is what I have dreamt all my life for," Felibert said. "It's pretty cool to see my name up there, but at the same time I have been trying to not think too much about it and just play one shot at a time and enjoy it.
"I'm having a lot of fun."
Brittany Lang had a 63 and is in a group at six-under par. Lang's 63 was the best round of the week.
Lang is tied with LPGA Championship winner Feng Shanshan of China (70), Katie Futcher (67), Ryann O'Toole (68) and Ai Miyazato (68).
World number one Yani Tseng, of Taiwan, followed her opening round 73 with a 74 as she missed her first cut in more than a year.
Tseng, who missed the cut by four shots, is the two-time defending champion of this event and a three-time winner this year.
Wie also didn't make it to Sunday, missing the cut for the sixth time in her last seven tournaments.