Daly City, CA (Sports Network) - Ariya Jutanugarn moved two steps closer to defending her title at the U.S. Girls' Junior Championship on Friday, taking two decisive victories to advance to the match play quarterfinals.

A 16-year-old from Thailand, Jutanugarn earned a 5 & 4 victory in the second round against Katelyn Dambaugh before storming to an 8 & 6 rout over Ashlan Ramsey in a third-round matchup at Lake Merced Golf Club.

The third-ranked female amateur, Jutanugarn was the stroke play medalist for the second straight year. She is looking to become just the third player in history to successfully defend her title at this championship. The only other players to do so were Judy Eller (1957-58) and Hollis Stacy (1969-71).

Also on Thursday, Lydia Ko of New Zealand moved on to the quarterfinals. The top-ranked female amateur, Ko rolled to a 7 & 6 win over Hee Wook Choi before defeating Nicole Morales by a 2 & 1 margin. Ko birdied the par-4 16th to gain a 2-up advantage, and won the match after the two halved the 17th.

Jutanugarn's opponent Friday will be Casie Cathrea, a California native who advanced into the quarterfinals with a 6 & 4 victory over Anne Freman. Cathrea had beaten Karen Chung, 2 & 1, earlier Thursday.

Ko will face Yueer Feng, a 3 & 2 winner against Euna Pak in the second round and a 6 & 4 winner against Summar Roachell in the third.

In the other quarterfinal matches, Kelli Murphy will face Minjee Lee, and Alison Lee will take on Lauren Diaz-Yi in an all-California matchup.

The quarterfinals and semifinals are scheduled for Friday, while the 36-hole final is set for Saturday.

07/19 21:02:14 ET