Pak is at 13-under-par 200. Pressel, who won this year's Kraft Nabisco Championship, posted a 7-under 64 Saturday to stand at 11-under 202 after three rounds.
In-Kyung Kim birdied seven holes in a row to start her Saturday round and finished with a 65. She is third at 205.
Alena Sharp (67) is at 206.
Pak, a four-time winner of the event, began the third round with a five-shot lead. But she three-putted the par-three second for a bogey before making birdies at four and six.
Pressel made three straight birdies around the turn.