Erynne Lee became the only tri-medalist to advance to the round of eight, notching two victories at the U.S. Women's Amateur on Thursday.
Lee followed a 1-up victory against Moriya Jutanugarn with a 3-and-1 win against Lizette Salas.
"I had the feeling that I would play well," Lee said. "My game was up to par, but I didn't feel like it was outstanding. But then practicing out here and playing the first two stroke play matches, I felt like I had a shot to win. Everything was solid."
Co-medalist Rachel Rohanna, who set an event record with an opening 65 in stroke play, rallied from 3 down against Marina Alex, but lost after a bogey on No. 19.
The other co-medalist, Jacklyn Sweeney, lost 5 and 3 when Junthima Gulyanamitta had birdies on three straight holes to clinch.
Lee's next opponent, Jessica Korda, was one of three golfers to advance with extra-hole victories in the third round.
Korda, who defeated Lee in the third round of the U.S. Women's Amateur last season, had a birdie on the second extra hole against Lisa McCloskey to complete a comeback in a match she called one of her toughest.
"I'm going to need to put some ice on a lot of parts of my body," said Korda, 17, whose father, former tennis star Petr Korda, served as caddie. "Lisa just played some great golf. I was down 10 holes and I didn't get a break until 16, where I could really come back to do something."
It took Kristen Park 20 holes to defeat Alex, who eliminated Rohanna in the morning session. She'll face Jennifer Kirby, who had to knock out Sara-Maude Juneau, a teammate on the Canadian national team, 1-up, by rallying from 3 down.
"You can never just sit back and get comfortable, even if you are up," Kirby said. "For me, I just had to keep grinding away because I knew that she was a good player. I know her very well, so I knew she wasn't going to let me win easily."
Sydnee Michaels earned a spot in the quarterfinals Friday with a win in 19 holes against Jungeun Han. Stephanie Sherlock, the third Canadian in the quarterfinals, will face Gulyanamitta.
Quarterfinals are Friday and semifinals Saturday on the par-72, 6,559-yard course. The final will be 36 holes on Sunday.