The Women's British Open is In-Kyung Kim's to lose after the South Korean shot a faultless 66 to pull six strokes clear with one round to play at Kingsbarns.
Kim has often contended in majors, registering seven top-five finishes, but now has a golden chance to claim a maiden victory.
Her lead stood at three shots when England's Georgina Hall birdied the 13th, 14th and 15th holes on Saturday. However, Hall (70) then bogeyed 16 and dropped two shots on the penultimate hole to slip back to 11 under alongside Moriya Jutanugarn (67).
There were no such problems for Kim, who birdied four of her first seven holes before finding further gains at the 11th and 12th to reach 17 under.
Having maintained her concentration superbly amid afternoon showers, Kim is now firmly on course to beat the record winning score at the Women's British Open, Karen Stupples' 19-under aggregate recorded at Sunningdale in 2009.
This year's runaway leader already holds the record 54-hole score for the competition.
Prior to Kim's superb 66, Inbee Park charged up to 10 under by equalling the course record of 64 set by Michelle Wie on Thursday.
Ally McDonald (70) is alongside Park, seven off the pace, while Stacy Lewis is one further back after a 65.