Ten players, including third-seeded Celine Boutier of France, earned a second consecutive group-stage victory on Thursday in the Bank of Hope LPGA Match-Play in North Las Vegas.
However, no players are guaranteed a place in the knockout round, with all 16 groups to be decided when round-robin play concludes on Friday at Shadow Creek Country Club.
The 64-player field is divided into 16 groups that are competing in round-robin play through Friday. The winner of each group will advance to single-elimination play.
Eight matches will be played Saturday morning, followed by four quarterfinal matches in the afternoon. The semifinals and championship match will be contested on Sunday.
Boutier downed the United States' Sarah Schmelzel 2 and 1 to sit atop Group 3 at 2-0-0. Boutier will oppose South Africa's Paula Reto (1-0-1) on Friday, with the winner advancing to the weekend. A tie would see Boutier move on.
The day's final match resulted in the biggest upset, as Switzerland's Albane Valenzuela defeated top-seeded Lilia Vu of the United States 2 up. Vu birdied the par-3 17th hole to cut her deficit to one hole, but she double-bogeyed the 18th as Valenzuela made par to seal the win.
"Definitely very happy to walk away with a win," Valenzuela said. "I mean, I knew this was going to be a very tough match. Lilia is undoubtedly one of the best players in the world and made me work for the points.
"She definitely left some putts out there, and I did as well, so we kind of fought till the end, but just happy to come out with a win."
Valenzuela leads Group 1 at 2-0-0, and she would advance if she can beat the United States' Lauren Hartlage (0-2-0) on Friday. Vu (1-1-0) opposes Denmark's Nanna Koerstz Madsen (1-1-0) to conclude group play.
Second-seeded Brooke M. Henderson also took a tight loss on Thursday, as the United States' Sophia Schubert beat the Canadian 1 up. In a wild match that saw the players halve just five holes, Henderson fell behind by making bogey on No. 17 as Schubert made par, and both players closed with a par.
"It was hard-fought," Schubert said of her win. "I knew going into it it was going to be a really good match. Brooke is an incredible player. She's a really tough competitor. So I just thought, you know, stay patient. It's going to go back and forth all day, but that is OK.
"If you lose a couple strokes, you can easily get them back out here on this course, it's so tough. So I just stayed patient all day."
Schubert and South Korea's Jeongeun Lee6 share the Group 2 lead at 1-0-1. Henderson is 1-1-0, and South Korea's Yaeeun Hong is 0-2-0.
In addition to Boutier and Valenzuela, the other players who are 2-0-0 are Thailand's Pajaree Anannarukarn (Group 4), Japan's Ayaka Furue (Group 6), Ireland's Leona Maguire (Group 7), Sweden's Maja Stark (Group 11), Spain's Carlota Ciganda (Group 12), the United States' Cheyenne Knight (Group 13), the United States' Ally Ewing (Group 14) and Sweden's Anna Nordqvist (Group 16).
--Field Level Media