Lilia Vu and Brooke Henderson were beaten on day two of the Bank of Hope LPGA Match-Play in Las Vegas but Leona Maguire and Celine Boutier were among the 10 players to make it back-to-back wins.
The event mirrors the PGA Tour's WGC-Dell Technologies Match Play, with players split into 16 groups of four for round-robin play before the knockout stages are contested at the weekend.
The last 16 will be played on Saturday morning followed by the quarter-finals in the afternoon, with the semi-finals and final on Sunday - you can watch the weekend's action live on Sky Sports.
Top seed Vu, who won the first women's major of the year, the Chevron Championship, in April, suffered a shock defeat to Albane Valenzuela with her Swiss opponent winning two up.
Vu had birdied the par-three 17th to cut her deficit to one hole but then double bogeyed the 18th as Valenzuela made par to seal the win, her second in as many days.
Valenzuela said: "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."
No 2 seed Henderson was defeated one up by Sophie Schubert but No 3 seed Boutier overcame Sarah Schmelzel 2&1 while Ireland's Maguire saw off Jenny Shin one up having beaten Linnea Strom 4&2 on day one.
In addition to Maguire, Boutier and Valenzuela, the other players who are 2-0 are Pajaree Anannarukarn, Ayaka Furue, Maja Stark, Carlota Ciganda, Cheyenne Knight, 2021 champion Ally Ewing and Anna Nordqvist.
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.
Watch the knockout stages of the Bank of Hope LPGA Match-Play live on Sky Sports Golf this weekend. Coverage begins at 11pm on both Saturday and Sunday.