Choi takes lead at Torrey Pines

South Korea's domination of the Samsung World Championship continued after the third round at Torrey Pines - but it was Na Yeon Choi who raced past her compatriot Jiyai Shin.

The latter led after 18 and 36 holes but was two strokes behind after 54, thanks to a nine-under round of 63 Choi.

In-form rookie Shin went round in 68. But Choi, who began the day three shots off the lead, had four birdies on the outward nine and - despite her only bogey on the 15th - never looked back.

Shin was still in front until faltering on the back nine.

Japan's Ai Miyazato shot a 68 for the third successive day to stand third - with heavyweights Lorena Ochoa and defending champion Paul Creamer tied for fourth.