She is looking to become the United States' third female major champion of 2023 after Lilia Vu's victory in the Chevron Championship and Allisen Corpuz's U.S. Women's Open triumph.

Ewing pulled off an eagle from five feet at the par-five 16^th hole to surge into first place in Surrey.

Ranked 39th in the world, she missed the cut in two of the last three majors while her most recent top-10 finish in such events came at the 2021 Chevron Championship.

"It's kind of funny, I missed my drive just a little bit right, it got hung up in the rough, and it was a situation where the ball was sitting down a little bit," said Ewing of her eagle.

"I happened to see both my playing competitors hit shots and noticed how firm it was up in front of the green.

"I actually was able to learn a little bit there and it was kind of gouge-type shot and I just let it chase, and it just so happened to chase to like five feet.

"You're trying to give yourself an eagle chance, and it just so happened to be a five-footer.

"I'm definitely happy to walk away with an eagle."

Ewing is followed close behind by a group of five players that finished on three-under-par after rounds of 69.

Gwangju 2015 World University Games champion Lee Jeong-eun of South Korea, Denmark's Emily Kristine Pedersen, Perrine Delacour of France, and Thailand's Jaravee Boonchant are all breathing down the leader's neck.

Lee's compatriot Amy Yang is also one stroke behind at two-under-par and, at number 45, is the only one of the chasing pack in the top 50.

Corpuz was among 12 players sharing seventh place on two under on a day in which some of the best players struggled despite favourable conditions.

Top ranked Nelly Korda of the US and number two from South Korea Jin Young-ko suffered disappointing starts as they both finished one-over-par on 73.

Defending champion Ashleigh Buhai has a lot of work to do if she is to retain her title.

The South African finished with a round of 74, putting her in joint 80^th place.