Australia's tilt at a second US Women's Amateur crown will head into match play at full strength.

After a day of fluctuating fortunes at Woodmont Country Club in Maryland, Gabi Ruffels, Emily Mahar and Kirsty Hodgkins all advanced to the knockout phase.

Defending champion Ruffels finished the weather-ravaged stroke play phase in a share of fifth today, earning the No.6 seeding for the second consecutive year with a dogged one-under-par 71 in tough scoring conditions.

After 36 holes split by a day off forced by Hurricane Isaias, it left the Victorian at one under and one of just seven players better than par with American medallist Rachel Heck at four under.

University of Southern California student Ruffels, who began her second round on the 10th tee, took a couple of holes to snap back to her best after a hectic couple of days.

"I actually had two finals (exams)," Ruffels said of the unexpected break in the tournament.

"I'm taking two summer school classes, (so) it actually worked out perfect that it was a day off because I could focus on my finals."

Ruffels started with a bogey on the long par-5 10th, then dropped another shot on the short par-4 12th to throw her out to two over.

But with her USC coach Justin Silverstein on the bag, the ground-breaking Aussie composed herself and didn't drop another shot as the field battled on a tough course made even harder by the weather.

"It definitely was a shaky start. I three-putted the first and then bogeyed my third hole, so I actually was really proud of myself the way I was able to get it back," she said.

"(Justin) just (told me) this course is tough, and it's playing tough ... (to) keep going and you never know what can happen. I was able to get it back with three birdies."

Mahar's ride was far more nerve-jangling.

The Queenslander began her day at one over, but was soon four over after a bogey on the second was compounded by a double-bogey on the fifth.

The Virginia Tech senior, though, is made of stern stuff these days and despite "burning the cup for 35 of the 36 holes", managed to craft a plucky 76 to finish at five over.

It left her in a slightly precarious position in a share of 70th after the morning wave, but with scoring far tougher than on day one after almost 7cm of rain on Tuesday (local time), she slowly but surely moved through the field to a share of 48th by day's end.

"It was agony," said Mahar, a member at Keperra in northern Brisbane who made her Australian representative debut last year in Texas.

"It went from no chance in my mind to hoping for a playoff, then just practising without really knowing ... through the afternoon.

"Then the (playoff number) started moving towards +6 and I was very relieved.

"I wasn't in any mental state to go back out and play."

Mahar eventually left the course just before 6.30pm local time, a full 12 hours after she arrived, "just relieved" after a two-day wrestle with the putter.

"I hit two flagsticks today - one for birdie and one for eagle, I've been burning the cup (both days) and haven't had anything drop ... bar one 20-footer for par on the 16th today, which I suppose was pretty important now and kept my spirits up."

Hodgkins, a University of Colorado senior playing in the afternoon, had a far better idea of the numbers game while she was on course.

The Redcliffe member didn't ride the same rollercoaster as her fellow Queenslander, but a couple of late bogeys got the mind racing.

Hodgkins, who started at one over today, had been one over for her round through 11 holes and seemingly cruising to a high seeding.

But bogeys on the 12th, 13th and 17th holes dragged her back alongside Mahar in a share of 48th at five over in total.

Hodgkins will take the No.52 seed into match play, while Mahar will be No.56.

"That seeding is just a number now. It doesn't matter what you've shot to get here," Mahar said.

MATCH PLAY DRAW and TEE TIMES