Yang and Ko were two shots off the lead of Thailand's Patty Tavatanakit, but overhauled that with a round of 67, bringing them down to eight-under par.

Ko showed promise yesterday with five birdies in her last 11 holes after a double bogey and a bogey within four holes.

Today, that good form continued with five birdies.

Yang putted seven birdies, but did have a bogey in the third and 15th rounds.

The South Koreans were part of a group of 14 golfers on three-under yesterday, with three from that pack also emerging a shot behind on seven-under par.

Atthaya Thitikul of Thailand was looking likely to sit at the top of the standings after putting four birdies in the first six holes, but two late bogeys halted her from joining Ko and Yang.

She is joint third with Brooke M Henderson from Canada and United States' Megan Khang.

Tavatanakit faltered down the table after finishing on two-over par for the day, now on three-under par overall.

American Danielle Kang and South Korea's Inbee Park had difficult days too, only able to move to five-under par after being a shot off the lead yesterday.

Round of the day went to American Yealimi Noh, who went under par on six holes in a row, including scoring an eagle on the eighth.

Despite also scoring an early bogey, she scored eight-under par for the day for a score of 64, moving her level with Kang and Park in 10th on five-under.