At 2-under 211, Kerr was the only player under par after 54 holes.
South Korea's Eun Hee Ji shot a 1-under 70 Saturday and moved into second place at even-par 213. Jean Reynolds (74) and Taiwan's Teresa Lu (70) shared third place at 2-over 215.
Paula Creamer, who had been just one shot off Kerr's 36-hole lead, fell eight strokes back after an eight-over 79 -- one of the worst rounds in Saturday's difficult day for scoring.
Copyright 2009 by United Press International.