Overnight leader Peter Uihlein of the United States shot a 4-under 68 to take a two-stroke clubhouse lead at the Perth International during Friday's second round.
Uihlein, who birdied his final two holes after starting on the back nine, had a two-round total of 11-under 133 and a two-shot advantage over Australia's Rhein Gibson, who also shot 68.
Louis Oosthuizen, the 2010 British Open champion, had an afternoon start at Lake Karrinyup after opening with a 70.
European Ryder Cup player Victor Dubuisson of France followed his opening 77 with a 71 and was 4-over and expected to miss the cut in the European Tour and Australasian PGA event.
Australian Marcus Fraser, who won in Malaysia last week, shot 73 and was nine strokes behind but inside the cut line.