It wasn't as long as the 30-hole match between Chia Yen Wu and Lauren Stephenson two years ago, but Thursday's Round-of-16 bout between Andrea Lee and Alexa Pano at the U.S. Women's Amateur was quite the marathon showing.

Lee sunk a birdie on the final hole of regulation to force extra holes and continued to hang with the consistent Pano until taking her first lead of the match with a winning par on the 23rd hole at Old Waverly Club in West Point, Miss.

Pano found a brutal lie off the tee on the second trip to the par-4 fifth hole and was forced to wedge out of the thick, left rough. Pano left herself 10 feet for par but couldn't convert, as Lee calmly two-putted for par to punch her ticket to Friday's quarterfinals, where she will face Lucy Li, her 2018 Curtis Cup teammate and partner.

"I just really had to grind it out," Lee said. "Alexa played great all day, really consistent. ... I had a tough start at the beginning of the front nine but managed to turn it around and birdie a few holes coming in."

Lee, a rising senior at Stanford, played her first eight holes in 3 over with no birdies as Pano, a top junior, took a 2-up lead. Lee finally got a birdie putt to fall at the par-5 ninth, and added two more birdies at Nos. 14 and 15 to square the match. Pano's fifth birdie of the match, at No. 16, gave her a late lead, and Lee was 1 down going into the par-4 18th before sinking a 10-foot birdie to force extra holes.

"[No.] 18 was crazy, just to make that putt was incredible," Lee said. "My dad [and caddie] told me to pick a line and stroke it and just trust it. It felt amazing to see it go in."

From there, it was a battle. Matching pars at No. 1, trading birdies at No. 2, and then two straight halves with pars before the finish at the fifth.

Lee will be joined by fellow Cardinal senior Albane Valenzuela in the quarterfinals. Valenzuela will face Ohio State's Aneka Seumanutafa after beating Auburn freshman Megan Schofill, 4 and 3.

USC's Gabi Ruffels continued her stellar play, routing Stanford freshman Brooke Seay, 6 and 5. Ruffels has yet to reach the 16th hole in match play. She will play Alabama's Kenzie Wright in the quarterfinals.

The other quarterfinal matchup will pit 15-year-old Megha Ganne against fellow teenager, 16-year-old Caroline Canales.