Ai Miyazato fired a five-under-par 67 and was aided by a penalty on American Stacy Lewis on her way to seizing a four-stroke lead after the third round of the LPGA Founders Cup on Saturday.

Japan’s Miyazato, chasing her 10th career LPGA title, finished 54 holes at the $US1.5 million ($A1.45 million) event on 19-under 197 with Lewis, who could claim the world No.1 ranking with a victory, and South Korean Jee Young Lee third on 201.

Lewis thought she had fired a 66 but tournament officials conducted a video review of the actions of her caddie, Travis Wilson, in a bunker on the par-4 16th hole and assessed a two-stroke penalty for testing the sand.

That turned a par on the hole into a double bogey and gave Lewis a 68 for the round, doubling her deficit behind Miyazato entering the last 18 holes.

The caddie walked into the bunker and appeared to flex his feet while standing in place as Lewis asked a question about her upcoming bunker shot.

For world No.3 Lewis to become No.1, she would need to win the tournament and have top-ranked Yani Tseng, the defending Founders Cup champion from Taiwan, finish worse than third. Tseng shared 63rd on 214 after 54 holes.

For the second day in a row, Miyazato birdied three of the course’s four par-5 holes, this time gaining ground on the second, fifth and 15th holes. She also had back-to-back birdies at the par-4 12th and 13th holes.

Lewis made back-to-back birdies at the second and par-4 third, added a birdie at the par-4 seventh, then began the back nine with two birdies in a row and closed with a birdie, only to stumble back due to the penalty.

Karrie Webb is the best-placed Australian, eight shots off the pace after firing a third-round 66.