Choi, from Concord Golf Club, carded a second-round one over 73, which included a quadruple-bogey eight on the 18th hole (her ninth of the day).
The New South Wales state team No.1 regained her composure however and finished her round off with a one-under-par front nine of 35.
Choi’s two-round score of even par good enough to grab the No.27 seed for match play.
Kyriacou, a member at St Michael’s, had been teetering after an opening 75 left her with some work to do.
A determined, more consistent attitude to her golf and a clutch birdie on the 15th late in her round all but ensured the 2019 Women’s Australian Master of the Amateurs Champion‘s even-par was enough to advance.
Kyriacou will head into the matchplay phase seeded 54th, and has drawn highly fancied American American Brooke Seay.
It was Seay who sensationally knocked out Kyriacou’s state teammate Grace Kim in the recent US Girls’ Amateur on the 21st hole.