O'Hern played Coolum's testing course in 9-under par in the third round, matching Lonard's three round aggregate of 198.
Lonard shot his second straight 65 to hold his share of the lead, three strokes ahead of Australian Peter O'Malley, who is alone in third place at 201. Wade Ormsby, also of Australia, is a shot further back in fourth at 14 under.
O'Hern's rounds of 69, 66 and 63, matched by Lonard who shot 68, 65, 65, put him on target for his first major professional title since the 1999 Coolum Classic.
'I'm playing well enough (to win), and I love this course,' O'Hern said.
A win for O'Hern Sunday would end a run of near-misses since his last Coolum victory six years ago. He has had 56 top 10 finishes since 1999, six in the United States, 25 in Europe and 25 in Australia. Among those finishes are 12 second and 11 third placings.
His run of bad luck has been so pronounced that even Lonard, his playing partner Sunday, said he hoped O'Hern would win.
Lonard, who hasn't had a bogey in 54 holes this week, will still be bidding strongly for his third Australian PGA title. He won in 2002 and 2004.
O'Hern's round Saturday culminated with a birdie at 18 to give him a share of the course record held by American Bob Estes and Australians Ormsby, Stuart Appleby and Matthew Goggin.
'The biggest challenge will be to back up a round like that,' he said.
U.S. Open champion Geoff Ogilvy is eight shots back in a share of ninth at 10 under, while world No. 4-ranked Adam Scott is at 6 under going into the last round.
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