Ewing had seven birdies with the only blemish coming with a bogey on the final hole as she moved to 10-under.

Charley Hull kept local hopes alive with a 68 for a five-under total, which was good enough for a share of second place with American Andrea Lee and Japan's Minami Katsu.

Ewing said: "I know there’s going to be potentially a long turnaround with a late tee time (on Saturday), but I’m going to try and relax and be best recovered and prepared to tee off tomorrow,"

"Nothing I’ve done in the past 36 holes can do anything for me for the next 36, so I'm just going to be mentally prepared for each individual day that presents itself."

Gaby Lopez, Alison Lee, Kim Hyo-joo and Lilia Vu all stand six shots behind Ewing.

Hull said the weekend cannot come fast enough.

"I'm buzzing," the home favourite added. "I thought that was a great score by Ally (Ewing) this morning. It's good now. Just chase her down."

South African Buhai's inconsistency saw her mix five bogeys with four birdies for a total score of three-over as she became the fourth consecutive defending champion to miss the cut.

Celine Boutier of France, aiming for a third consecutive win following her triumphs at the Women's Scottish Open and Evian Championship, finished at one-over after a 71.