South Africa's former British Open winner carded a three-under-par 70 at The Lakes on Friday to climb above first-round pacesetters Jenny Shin of the USA and Sydney teenage prodigy Rachel Lee.
Buhai is seven under at the halfway point, one stroke ahead of Shin, who posted an even-par 73 at The Lakes, and also Lee, who has an afternoon tee time at The Australian.
After opening with a four-under 69 at The Australian on Thursday, Buhai made a fast start to her second round with three consecutive birdies from the second hole.
She reached the turn in eight under for the tournament but dropped a shot with two bogeys and a lone birdie on the back nine.
Teenager Justice Bosio in early morning round two action at the Australian Open in Sydney. (Dan Himbrechts/AAP PHOTOS)
Rising Queenslander Justice Bosio was another of the major morning movers, surging to fifth spot with a four-under 69 at The Lakes.
Runner-up in the Australian amateur championship the past two years, Bosio mixed five birdies with just one bogey to be at four under at the halfway stage of the Open.
But more fancied compatriots Grace Kim and Hannah Green could only manage 73s at The Lakes.
Kim remains at two under for the championship, and five strokes adrift of Buhai, with Green level with the card.
Pre-tournament favourite Minjee Lee, at three under, and Steph Kyriacou, at four under, were playing in the feature afternoon group at The Australian.
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