Most of the big names have bowed out of this U.S. Women’s Amateur, but one that remains is the world’s second-ranked amateur.

Rachel Heck, the Annika Award-winning Stanford sophomore who won the NCAA individual title and four other times as a freshman, took three straight holes to close out Arkansas senior Brooke Matthews in 19 holes in their Round of 16 match Thursday at Westchester Country Club in Rye, New York.

Heck, from Memphis, Tennessee, was coming off of an easy 7-and-6 victory of Australia’s Grace Kim in the previous round before going back and forth with Matthews for much of the match. After Matthews won Nos. 15 and 16 to take a 2-up lead, Heck responded, winning the par-4 17^th with a two-putt par and then draining a 15-foot double-breaker for birdie at the last to extend the match.

On the first playoff hole, the par-3 first, Heck found the green and took the match with another two-putt par.

“I think that's what this tournament is all about,” said Heck, who is trying to become just the second player to win the NCAA Women’s Championship and U.S. Women’s Amateur in the same year (Vicki Goetze was the first, in 1992). “You expect to have these kinds of matches. Really high pressure. My hands are shaking, my heart is beating so fast, but that's what's fun about it.”

Added Matthews, who eliminated Penn’s Elle Nachmann in the Round of 32: “You have to fight. You can't stop fighting. It doesn't matter who you're playing against. Anyone is beatable on the right day. You just never know when your day is going to be, so just keep fighting and someday you'll win the fight.”

Heck will advance to face Thailand’s Kan Bunnabodee in Friday’s quarterfinals, which will feature just three players ranked in the top 75 of the world rankings. Arizona’s Vivian Hou (21) will play 15-year-old Cara Heisterkamp, who isn’t even ranked in the women’s WAGR, while Virginia Tech’s Emily Mahar (74) will take on Kentucky’s Jensen Castle.

Heisterkamp routed Heck’s Stanford teammate and British Women’s Amateur champ Aline Krauter, 7 and 5, on Thursday afternoon.

“Well yesterday I had about like 115 [text messages], and I've gained like 50 Instagram followers on both my accounts,” Heisterkamp said. “It's all so exciting. I heard they were doing my trick shots from my golf account on TV, so I can't believe that.”

Mahar beat a 14-year-old, Rianne Mikhaela Malixi, in her Round of 16 match, chipping in from 80 feet at the par-5 18^th hole to secure the 1-up win. A day earlier, Mahar chipped in on No. 17 to beat Oklahoma State’s Maddison Hinson-Tolchard.

“I had the exact same shot this morning in my first match,” said Mahar, who beat Texas’ Sophie Guo in the morning, “so I mean [my caddie] walked up to me and she said, ‘At least you know how this one goes,’ even though this morning it was for eagle and this time it was to close it out. I just felt really confident in that spot on the green and knew that at worst I would get up and down; went in.”

ROUND OF 32 RESULTS

• Hailey Borja def. Marissa Wenzler, 3 and 2
• Valentina Rossi def. Valeria Mendizabal, 4 and 3
• Katie Cranston def. Tess Blair, 5 and 4
• Brooke Seay def. Emilia Migliaccio, 2 and 1
• Cara Heisterkamp def. Mika Jin, 4 and 2
• Aline Krauter def. Aneka Seumanutafa, 2 up
• Emma McMyler def. Cindy Kou, 3 and 2
• Vivian Hou def. Bibilani Liu, 8 and 7
• Jensen Castle def. Sophie Linder, 1 up
• Jenny Bae def. Anna Morgan, 1 up
• Rianne Mikhaela Malixi def. Valery Plata, 5 and 4
• Emily Mahar def. Sophie Guo, 1 up
• Brooke Matthews def. Elle Nachmann, 1 up
• Rachel Heck def. Grace Kim, 7 and 6
• Kailie Vongsaga def. Riley Smyth, 3 and 2
• Kan Bunnabodee def. Emma Spitz, 19 holes

ROUND OF 16 RESULTS

• Rossi def. Borja, 20 holes
• Seay def. Cranston, 2 and 1
• Heisterkamp def. Krauter, 7 and 5
• Hou def. McMyler, San Antonio, 3 and 2
• Castle def. Bae, 4 and 2
• Mahar def. Malixi, 1 up
• Heck def. Matthews, 19 holes
• Bunnabodee def. Vongsaga, 6 and 5

QUARTERFINAL MATCHUPS, TEE TIMES

• Valentina Rossi (WAGR: 288) vs. Brooke Seay (166), 1 p.m. ET
• Cara Heisterkamp (NR) vs. Vivian Hou (21), 1:10 p.m.
• Jensen Castle (248) vs. Emily Mahar (74), 1:20 p.m.
• Rachel Heck (2) vs. Kan Bunnabodee (212), 1:30 p.m.