Royal Adelaide's Caitlin Peirce finished as the top non-American in the US Women's Amateur Championship after making it through to the final 16 at the Bel-Air Country Club in Los Angeles today.

Peirce won her round of 32 match 3&1 against Casey Weidenfeld (US) before being eliminated on the 19th hole by another American, Megan Schofill, in their afternoon duel to decide the quarter-finalists.

Reaching the last 16 matched Peirce's performance at last month's British Women's Amateur Championship where she was also the leading Australian.

Peirce dominated her morning match with Weidenfeld, winning the second, third and seventh holes to establish a 3 up advantage.

After losing her first hole to a Weidenfeld birdie at the ninth, she seized control with back-to-back wins at the 13th and 14th.

Although the American rallied late with birdies at the 15th and 16th to cut the lead to 2 up, Peirce sealed the match with a par at the 17th.

The South Australian's great fighting spirit which was on show in her first matchplay encounter on Wednesday returned in the round of 32 match-up against Schofill when she quickly fell 3 down.

Peirce was still two holes behind when she came to the 16th tee but she won that hole with a par and then birdied the 18th to level up the contest for the first time since the opening hole.

Schofill's birdie on the first extra hole ended Peirce's first US Women's Amateur challenge.