The first preteen showdown in the 107-year history of the US Women's Amateur golf championship went to Alexis Thompson.
The 12-year-old seventh-grader from Florida, already the youngest qualifier in US Women's Open history and the recent Junior PGA champion, beat Pearl Jin 5 and 4 on Thursday in the second round at Crooked Stick Golf Club.
Thompson and Jin, also 12, were the youngest qualifiers to reach match play in the Women's Amateur.
Thompson birdied three of the first six holes, including a 2.3m putt on the par-3 No. 6, and went 5-up after eight.
They halved the next six holes to finish their match, sending Thompson to the next round against 18-year-old Lizette Salas.
"It's a great experience," Jin said of the preteen matchup. "My swing was off today. I didn't hit the ball solid, and my putts just didn't go in. I was nervous today. It affected my swing and my putting rhythm and tempo."
Salas advanced to the third round by beating Kira Meixner of Canada in 19 holes.
Also eliminated in the second round was co-medalist Kristina Wong, who lost to Vicky Hurst 3 and 1. The other co-medalist, US college champion Stacy Lewis of Arkansas, lost in the first round on Wednesday. No medalist has won the women's amateur since Meredith Duncan in 2001.
Other second-round winners included Amanda Blumenherst, a 10th-place finisher in the US Women's Open last year, who beat Jenny Suh 5 and 4.
Andrea Messer, who had to go a record-tying 27 holes to win her first-round match on Wednesday, played only 13 holes in the second round before losing to Tiffany Joh 6 and 5.