What it means: Chun won last year's U.S. Open, and now she is in position to join Se Ri Pak as the only players to make their first two wins major titles. Chun made three birdies through eight holes and held a five-shot lead until a double bogey at the par-5 ninth. She rebounded with three birdies and a chip-in eagle at the par-5 15th to extend her lead.
Round of the day: I.K. Kim and Jodi Ewart Shadoff both fired the low round of the day with a 7-under 64. Kim birdied five of the last six holes and sits in fifth place, while Shadoff recorded seven birdies and no bogeys to move just outside the top 10.
Best of the Rest: Chun and Sei Young Kim both turned in rounds of 6-under 65. Kim made six birdies and no bogeys to move into seventh place.
Biggest disappointment: Brittany Lincicome started the day only five strokes back, but she hit two balls into the water and made a quadruple bogey at the par-3 5th on her way to a 3-over 74.
Storyline to watch: Chun is in the driver's seat for her second major, and she will also have a chance to break the lowest score in relation to par (19 under) and the lowest overall total of 267. Weather will also be a factor for the final round. With a 100 percent chance of rain in the afternoon, tee times have been moved up for Sunday.