World No 1 and defending champion Nelly Korda beat Jennifer Kupcho 1-up on Thursday to keep alive her hopes of advancing to the knockout stage of the LPGA Match Play in Las Vegas, Nevada.
Korda survived what she called "very questionable" play coming down the stretch against Kupcho.
She went 2-up with a par at the 12th hole and remained 2-up despite a bogey at 15.
But Korda's bogey at the par-five 16th saw Kupcho claw back a hole before Korda closed out the win as they tied each of the last two holes with pars.
"Definitely don't have my best stuff right now," said Korda, whose victory at Shadow Creek golf course last year was one of her seven LPGA titles in 2024.
"That's the greatest thing about match play is even if you don’t have your best stuff you have to grind it out."
Korda, who tied her opening match against Brittany Altomare on Wednesday, faces a must-win match on Friday against Thailand's Ariya Jutanugarn, who beat Altomare 2&1 on Thursday to improve to 2-0.
The winner of each of the 16 four-woman groups advances to the knockout round.
The format is a change from last year, when the top eight players after three rounds of stroke play advanced to weekend match play.
If there is a tie for first in a group, a playoff will determine the group winner.
South Korea's Kim Hyo-joo and Sweden's Maja Stark were tied with two wins each atop their group. Kim won the last four holes to beat Denmark's Nanna Koerstz Madsen 2-up.
Stark beat Bailey Tardy 3&2 and will meet Kim on Friday to decide who advances.
Stark said going head-to-head to win the group wouldn't affect her strategy against Kim, who won the Ford Championship in a playoff on Sunday.
"I don't know how Hyo-joo has been playing, but since she won last week I'm guessing she's been playing really well," Stark said. "But I'm just going to try to focus on my game and take one shot at a time."
World No 2 Jeeno Thitikul improved to 2-0 with a 2&1 victory over Gaby Lopez.
Other players emerging from the first two round-robin days with 2-0 records and in prime position to advance were Canadian Brooke Henderson, France's Celine Boutier, South Koreans Kim A-lim, Kim Sei-young and An Narin, Sweden's Madelene Sagstrom, Japan's Mao Saigo and Australian Stephanie Kyriacou.
World No 3 Lydia Ko of New Zealand kept herself alive in a tight group with a 6&5 victory over Australian Gabriela Ruffels.
While Ko said she thought a "cut-throat" single elimination format, with the loser of each match eliminated, was more in keeping with the match play vibe, she was delighted to still have a shot at the weekend.
"Yesterday I came off the day not feeling, like, defeated, she said. "You still get two more chances, so I'm excited for tomorrow."