Australia's Karrie Webb broke her own course record with a 10-under-par 62 in the third round of the ANZ Ladies Masters at Royal Pines on the Gold Coast.

The world number three came from seven strokes behind overnight leader Sun Ju Ahn of South Korea to finish the day tied for the lead with compatriot Michelle Ellis on 15-under.

Webb's 62 bettered her previous course record of 63, which she set in 1999 and which Ai Miyazato and Tiffany Joh equalled in 2005.

It was the best score in the 18-year history of the ANZ Ladies Masters and just one stroke short of Webb's personal career best, an 11-under-par 61 at the 2000 Oldsmobile Classic in Michigan.

"It was one of those days where it felt as though the hole was as big as a bucket," said Webb.

"I was just trying to keep making birdies and was in such a good groove, especially on the greens. It was one of those days when everything was on my side."

Webb carded 10 birdies and took the outright lead after 15 holes but hit a bunker on 18 and had to putt to save par.

Webb posted rounds of 71 and 68 on the first two days and played with Taiwan's Ruby Tseng and Welsh ace Becky Brewerton in the third round.

Brewerton, entering her fourth year with the Ladies European Tour, carded a 68 for a nine-under-par aggregate and a share of eighth position.

Ellis shot a 68 and will play with Webb and Wahlin in the final group tomorrow.

Ji Yai Shin of South Korea sits just one shot adrift on 14 under after a third-round 66 and a trio of players - Ahn, Lotta Wahlin and Cristie Kerr - are two shots further back.