Grace Kim and Emily Mahar are through to the round of 32 at the US Women's Amateur at Westchester Country Club.

It was a choatic opening round of match play with only three of the top ten seeds claiming victories, while the highest seeded Australian was also knocked out.

Seeded 23 after the stroke play rounds, West Australian Maddison Hinson-Tolchard could not get the better of number 42 seed Mahar in their All-Aussie match-up.

It was a tight contest as score jumped between tied and Mahar one up during the opening eleven holes before Hinsom-Tolchard finally managed to create a lead of her own and went two up after 14 holes.

From there it was all Mahar, the Queenslander stormed home with a par-par-birdie-birdie to finish to win the final four holes and claim victory, two up.

New South Wales' Grace Kim also came from behind to win her match against Canadian Celeste Dao.

Kim was two down at the turn and chipped away throughout the back nine to finally claim victory on the last hole, one up.

The match was all tied heading to the 18th - the longest hole on the course - and Kim found her composure to make two nerve-wracking putts despite a difficult day with the flat stick.

"I just didn't hole a putt," Kim told Golf NSW.

"It was a challenge and a test of patience because I kept hitting good shots."

Kim's next opponent is American Rachel Heck after she was dominant in a 7 & 5 win over compatriot Karen Tsuru.

Meanwhile, Mahar will face China's Sophie Guo, whose match with American Maisie Filler ebbed and flowed before she secured a 3 & 2 victory by winning the 14th, 15th and 16th holes.