Peter Lonard, who briefly seized the lead with four birdies through 13 holes, hooked his drive at the last hole so far off line that it landed in a bunker along the 10th fairway. He wound up with a double-bogey six for a 70 and sole possession of fourth place at 10-under-par.
1996 Australian Amateur champion David Gleeson (68) and Mathew Goggin (70) finished together at 9-under, while New Zealand's Gareth Paddison (70), who is making his professional debut this week, joined Nick O'Hern (70) four shots off the pace at 8-under.
Allenby, who also held a one-stroke lead after each of the first two rounds at Royal Queensland Golf Club, quickly pushed his advantage to three shots at 13-under with a birdie at the par-4 1st hole and an eagle at the par-5 3rd.
He dropped shots at the 10th and 12th holes, just his second and third bogeys of the tournament, before he picked up his final birdie of the day at the 13th.
The 30-year-old Allenby is coming off his second straight two-win season on the U.S. PGA Tour. Should the man from Melbourne hold on to win Sunday, he would become the first player to win back-to-back Australian PGA titles since Greg Norman in 1984-85.
'Normally if I am up there with a chance to win, it is not too often I will lose from there,' said Allenby, the top-ranked Australian at No. 26 in the world. 'Tomorrow I will go out there and back myself on every shot and play as aggressive as I need to, depending on how the others play.
'I've got to go out there and try to shoot five or six-under.'
Ogilvy made his way toward the top of the leaderboard with six birdies against two bogeys in round three.
The 24-year-old finished second to World No. 1 Tiger Woods at the Johnnie Walker Classic in Thailand a year ago, then got off to a hot start in his first season on the U.S. PGA Tour with a tie for third at the Tucson Open and joint second at the Honda Classic.
Although he struggled the rest of the year in the U.S. with 13 missed cuts over his last 17 starts, Ogilvy still managed to finish 95th on the 2001 money list and kept his playing card for the 2002 season.
Parry, who captured the 1992 Australian PGA Championship with a tournament-record total of 19-under-par 269, carded a bogey and eight pars on the front side Saturday but battled back with three birdies on the inward nine.
Norman, who was inducted into the World Golf Hall of Fame last Sunday, had a promising start with a 68 on Thursday but is currently tied for 27th after rounds of 73-72 over the last two days.
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