For the second consecutive year, all four semifinalists in the U.S. Women’s Amateur Championship will be golfers who have yet to start college. In fact, at 18 years of age, Bethany Wu, of Diamond Bar, Calif., is the elder stateswoman. The Women’s Amateur has not had a champion over the age of 19 since Amanda Blumenherst in 2008.

Such is the current nature of women’s amateur golf.

But going by the Women’s World Amateur Golf Ranking™, the four semifinalists are Nos. 5, 9, 10 and 40, with No. 5 Sierra Brooks, of Sorrento, Fla., the highest. So while they might be young, they are accomplished.

A look at Saturday’s two semifinal matchups, with seeding in parentheses:

Hannah O’Sullivan, Chandler, Ariz. (32) vs. Mathilda Cappeliez, France (28)

O’Sullivan, 17, is back where she was a year ago at Nassau Country Club, and she’ll once again have to get past a strong international golfer to reach Sunday’s 36-hole championship match. O’Sullivan, No. 10 in the WAGR, fell to Brooke Mackenzie Henderson, of Canada, in 2014. This year, she draws Cappeliez, who finished 59th in the 2014 U.S. Women’s Open. Cappeliez, competing in her third USGA championship and second U.S. Women’s Amateur, failed to qualify for match play in 2014 at Nassau C.C.

O’Sullivan, who has announced intentions to attend the University of Southern California in the fall of 2016, had needed just 39 holes to bounce her first three foes. But she was stretched to the limit in the quarterfinals, prevailing 1 up against Lindsey McCurdy, 20, of Liberty Hill, Texas.

USGA experience clearly is on O’Sullivan’s side, having made match play in the U.S. Women’s Amateur five years ago at the age of 12 at Charlotte (N.C.) Country Club.

O’Sullivan, who tied for 53rd in last month’s U.S. Women’s Open, also owns international experience from playing in the Junior Ryder Cup, where she went up against Cappeliez in foursomes and singles. Cappeliez and her partner, Alexandra Forsterling, prevailed, 6 and 5, in foursomes, but O'Sullivan won the singles match, 2 and 1.

“She's actually a really good friend of mine, so we'll have fun out there, and it'll be a good match,” said O’Sullivan, who potentially could see Cappeliez again at next month’s Junior Solheim Cup in Germany.

Having already played in a U.S. Women’s Open, Cappeliez, No. 40 in the WAGR, won’t be intimidated by the Fox Sports 1 cameras or large galleries. And there’s no greater pressure than representing your country in the European Team Championship, a title France won earlier this summer. She also led France to the European Junior Championship in 2014.

The 17-year-old, who lives near the eighth hole of Evian Golf Club, the host site of the Evian Championship, is vying to become the second player from France to win the U.S. Women’s Amateur, and third to capture a USGA title. Catherine Lacoste won the title in 1969, two years after she won the U.S. Women’s Open (she remains the only amateur Women’s Open champion). Sandrine Mendiburu took the U.S. Girls’ Junior in 1990.

It’s been a big year for France already. In addition to the European Team Championship, Celine Boutier won the Ladies British Open Amateur at Portstewart in Northern Ireland, and Romain Langasque claimed the Amateur Championship at Carnoustie in Scotland. Another French professional, Alexander Levy, qualified for the U.S. Open at Chambers Bay and tied for 27th.

“That was awesome,” said Cappeliez, who is home-schooled and still is considering attending college in the U.S. next year. “I am really good friends with Romain, and Celine as well. She's always on my team, and I went to the [Ladies] British also, but I lost my second match. France is growing up and that's really good.”

Sierra Brooks, Sorrento, Fla. (18) vs. Bethany Wu, Diamond Bar, Calif. (14)

This is a rematch of a semifinal match in last year’s Polo Golf Junior Classic, the lone match-play event on the American Junior Golf Association circuit. Brooks, 17, prevailed en route to the title, so Wu, an incoming 18-year-old freshman at UCLA (she starts school next month), is looking to avenge that defeat to a good friend. As Wu was finishing up a post-match interview on Friday following her 5-and-4 win over Mika Liu, Brooks came by and gave her a high-five. Brooks eliminated Wu’s future UCLA teammate, Bronte Law, of England, 5 and 3.

“I'm friends with almost everyone,” said Wu, No. 9 in the WAGR. “[In] golf you've just got to be nice to everyone, be respectful, so you just end up getting along with everyone.”

Added Brooks: “Bethany is one of the funniest girls I know. There's no messing around with Bethany. You get the honest opinion every single time, and she's just a goofball. We always have so much fun together. She stayed at my house after SALLY (South-Atlantic Ladies Amateur), and we had sleepovers and went to Universal [Studios in Orlando], and we try to play together in every single practice round. I always have fun when I'm with her, and I always enjoy that time I get to spend with her.”

Wu might have a friendly outward demeanor, but there is plenty of competitive fire. She has only played 14 holes in each of her last two matches, and her game seems to be peaking at the right moment. Two weeks ago, she was runner-up to Mariel Galdiano at the Canadian Women’s Amateur. She also reached the championship match of last month’s North & South Women's Amateur, falling to Bailey Tardy. But since she began working with instructor Bryan Lebedevitch in May, Wu has witnessed improvements, specifically getting her swing more on plane and a straighter ball flight.

“We’ve only had three or four lessons, so I think it’s been a good change.”

Wu, who plans to major in psychology, also would like to join past UCLA Bruins Kay Cockerill (1986-87), Jane Park (2004) and Mariajo Uribe (2007) on the Robert Cox Trophy. Two other Bruins, Erynne Lee (2008) and Alison Lee (2013) were semifinalists.

“I think Coach [Carrie Forsyth] just texted me,” said Wu, whose best showing in six previous USGA was a trip to the semifinals of the 2013 U.S. Girls’ Junior. “I think I want to keep that legacy going.

“Getting runner-up in my last two events has given me an opening to see if I can win this one. All things happen for a reason.”

Brooks, who plans to attend Wake Forest in 2016, is no stranger to winning big events, either. Besides the 2014 Polo Classic, she won the 2014 South-Atlantic Ladies Amateur and 2015 Women’s Southern Amateur. She also was the 2014 Florida State 1A high school champion. USA Today named her its female high school golfer of the year.

Like Wu, Brooks also has international experience, having teamed with her in last year’s Junior Ryder Cup in Scotland. Brooks will play for the USA in the Junior Solheim Cup in September, something Wu did two years ago.

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