One of Lauren Stephenson’s earliest golf memories is going to the Ginn Tribute at Rivertown Country Club in Charleston, S.C., and watching her idols on the LPGA Tour. At age 8, Stephenson obtained a signed glove from 2005 U.S. Women’s Open runner-up Morgan Pressel.

A decade later, Stephenson is again among her idols, but the Lexington, S.C., resident is signing autographs, not seeking them.

Stephenson, who brought the signed glove from Pressel with her this week, is one of 26 amateurs competing with the world’s best players in this week’s U.S. Women’s Open at CordeValle. For those amateurs, the challenge is focusing on the golf and not being awed by the surroundings.

On Monday, Stephenson played a practice round with world No. 1 Lydia Ko, who was born a few months earlier in 1997 but has won 13 LPGA Tour titles, including a pair of majors. Stephenson will be a sophomore this fall at the University of Alabama after transferring from Clemson and is believed to be the first player to be named all-state in both boys’ and girls’ golf.

“I told my mom, it’s so weird that I am going to play with a millionaire who is the same age as me,” said Stephenson, who turns 19 on July 13. “But once you get on the golf course, it’s the same thing as any other tournament. It’s the same game, but just with all these amazing people.”

Playing the U.S. Open for the first time can be a little overwhelming, even for professionals. While amateurs aren’t competing for prize money, the “wow” factor is prevalent. Crowds are bigger, the courses tougher and then there is the inherent star power.

If you’re Naomi Eun Yong Ko, 18, of Canada, there are inquisitive looks and questions. Many want to know if she is related to the other Ko.  The question is flattering, but the answer is no.

“Quite frequently,” said the North Carolina State sophomore when asked how many times people ask her about being related. “She is the No. 1 player in the world, so it is nice to see that. I have never met her.”

Ko got a head start on this week’s test by qualifying for last week’s LPGA Tour event, the Cambia Classic at Columbia-Edgewater Country Club in Portland, Ore. Playing in the pro-am with tour pro and countrywoman Alena Sharp helped ease her anxieties.

“By the time I got to the first round [on Thursday], I was OK,” said Ko. “It got better as the week went on.”

Ko is trying to incorporate some of the intangibles – like practice and preparation – that she observed among the pros last week. On Monday, she played with world No. 2 and fellow Canadian Brooke Henderson, who is also 18 but already owns three LPGA victories, including a major (2016 KPMG Women’s PGA Championship).

“It does give me confidence,” said Ko. “Brooke has been good for a long time. I watched her on 18 [on Sunday in Portland where she won] and it was amazing how well she kept herself grounded.”

Just because there is an (a) next to their name on the tee sheet, doesn’t mean the amateurs can’t compete. Catherine Lacoste, of France, is the only amateur to win the U.S. Women’s Open (1967), but others have come dramatically close to hoisting the trophy. Jenny Chuasiriporn lost a 20-hole playoff duel with Se Ri Pak in 1998 at Blackwolf Run. Birdie Kim holed out a bunker shot on the 72nd hole to wrest a possible win from 17-year-old Morgan Pressel in 2005 at Cherry Hills Country Club. Pressel would share runner-up honors with fellow amateur Brittany Lang. That same year, Michelle Wie led after the first and third rounds, only to shoot a final-round 82 and tie for 23rd.

Seven of the top 20 in the Women’s World Amateur Golf Ranking™ (WAGR) are competing at CordeValle, including world No. 1 and 2015 U.S. Women’s Amateur champion Hannah O’Sullivan, 18, of Chandler, Ariz., and world No. 2 and 2015 Mark H. McCormack Medal winner Leona Maguire, 21, of the Republic of Ireland. Albane Valenzuela, 18, of Switzerland (No. 11 in the WAGR) shared low-amateur honors with O’Sullivan at the ANA Inspiration in March. Valenzuela and Maguire both are likely to represent their countries in next month’s Olympics.

O’Sullivan, world No. 5 Sierra Brooks, No. 9 Bailey Tardy and No. 19 Mike Liu were all members of the 2016 USA Curtis Cup Team and all are in the field this week.

And Karah Sanford, 14, of San Diego, is the youngest player in the field.  She made the cut earlier this year in the Volunteers of America Texas Shootout on the LPGA Tour and was a finalist two years ago in the inaugural Drive, Chip & Putt Championship at Augusta (Ga.) National Golf Club.

Valenzuela, who will enroll at Stanford University in the fall, has already posted top-five finishes in a pair of Ladies European Tour events this year, so playing against professionals isn’t overwhelming.

“I’ll just play it like it’s another tournament,” said Valenzuela, who was born in New York City and has lived in Mexico and Switzerland. Both of her parents are French. “I just want to have fun and we’ll see what the outcome will be.”

Maguire, the 2015 Annika Award winner as college golf’s player of the year and the low amateur in last year’s Evian Championship, echoed similar sentiments about her third major-championship start. She said playing in front of a boisterous Curtis Cup crowd at Dun Laoghaire in Ireland helped in her preparation. She has also played college events in California, so is accustomed to the turf and weather. 

“Weeks like this are a bonus for me,” said the Duke University junior. “I’m just trying to enjoy the week as much as possible. I played a practice round with [2014 U.S. Women’s Open champion] Michelle Wie [on Monday] and were joking around quite a lot. She knows what it takes to win events like this. It was nice to see her prepare and see what she does on a practice round.

“Obviously week in and week out we’re not use to playing these kinds of golf courses in this kind of environment, but who knows what can happen on the weekend. Even for me, Stephanie Meadow [of Northern Ireland, a 2012 Curtis Cup teammate] nearly won at Pinehurst [finishing solo third in her professional debut]. A lot of the girls out here are very, very good … but anybody if they play their best has a chance of winning.”

David Shefter is a senior staff writer for the USGA. Email him at dshefter@usga.org.