"It was kind of bittersweet always to announce that, but it's something that I've been thinking about for a while," admitted Wie West, who won the tournament in 2014.

"I'm extremely proud to have achieved the two biggest dreams that I've had, one being graduating and the other winning the US Open, I'm very proud of myself.

"I've always wished I would have done more, but I feel like everyone kind of feels that way, so I'm definitely giving myself some grace and enjoying this last week."

She gave birth to daughter Makenna in 2020, and insists the US Open next year will be her last.

The tournament prize money has been increased to $10 million (£8 million/€9.38 million).

The winner is set to take away $1.8 million (£1.4million/€1.69 million).

"Huge kudos to the USGA for really buying into the women's sport and the LPGA for just growing and keep pushing the boundaries," Wie West added.

"When doors get closed on us, we just keep pushing, and I'm just so proud of everyone on tour and the USGA for really buying in and setting the level right."

World number one Jin Young Ko of South Korea is chasing the third leg of a career Grand Slam and starts as a favourite.

"I don’t have only one rival, I have lots of rivals in this tour," Ko said.

"My caddy David Brooker, he knows this golf course well so he will help me.

"I really want to play this golf course, I heard about this gold course, that it's a tough one, but it is going to be fun."

A play off victory last year catapulted Yuka Saso of the Philippines into the spotlight.

As she returned the trophy earlier this week she admitted: "It was amazing. 

"It was life-changing, and at the same time, to have the trophy for a year, it was awesome." 

World number three Lydia Ko of New Zealand has not finished outside the top 25 so far this season.

"I started off my season well winning the second tournament of the year," she said.

"I still feel like there's a lot of things to work on just to be a little bit more consistent throughout my game, I don’t think anyone ever feels that they’re perfect, there’s always things that can improve even when things are going well."

The field also includes Olympic champion Nelly Korda who returns after surgery for a blood clot.

"I'm honestly just grateful to be out here, I'm going to take it one step at a time, I'm not expecting too much," Korda said.

She is playing her first tournament since February.

International Golf Federation President Annika Sörenstam, a three time champion, earned an exemption to compete after winning the US Seniors last year.

"I have been practising, to play well here I’ve got to really max out my game, trying to find a balance working on my swing and also playing," Sörenstam said.

"I’m not really going to have a score in mind but I feel good about my game I really do."

A field of 156 will set out on Thursday and the top sixty and ties will make the cut at 36 holes for the weekend.