A bogey on the final hole saw Adam Scott drop into a share of the Australian Masters lead alongside countryman Peter Wilson following Friday's second round.
The world number 12 started Friday's round with a one-stroke advantage at the top of the leaderboard and at the midway point of his second round, that advantage had been stretched to five strokes.
However, the former world number one had a disastrous back nine, notching up a double bogey on 10, a bogey on 13 and then another bogey on 18 to finally sign for a one-under 70 and a 36-hole score of eight-under-par 134.
Wilson, meanwhile, carded successive 67s to share the lead at the halfway mark.
A stroke back in third place was Matt Guyatt (69), while Brett Rumford shot the day's low round of 64 to be tied for fourth, alongside George McNeill (66).
Steven Bowditch, the second-highest ranked player in the field, and big-hitting Belgian Nicolas Colsaerts both missed the cut.
The Englishman carded a 66 to put behind him the disappointment of playing alone and missing the cut last week.
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