American Jordan Spieth shot a 2-under 69 to move into a three-way share of the lead at the Australian Open after Saturday's third round.
Adam Scott stayed close while defending champion Rory McIlroy dropped five shots in two holes and shot 76.
Spieth, second-round leader Greg Chalmers (71) and fellow Australian Brett Rumford (69) had three-round totals of 5-under 208 on a tough Australian Golf Club course and its swirling, unpredictable winds. Only eight players were under par.
Scott shot 69 and was tied for fourth, a stroke behind the leading trio, along with Australian veteran Rod Pampling (69).
McIlroy, who had a triple bogey on the ninth hole and a double-bogey on 10, was six strokes from the lead, tied for 14th.
He was tied for the lead at 4-under and even on the day when he hit his tee shot on the par-4 ninth into waist-high rough. After failing to advance it and burying it in matting used to control weeds, he took a penalty drop, sliced that and finally got on the green in 5, where he two-putted for 7.
The Northern Irishman and world No. 1 then hit his approach on 10 into woodchips, failed to advance it back to the grass on his next shot, and two-putted for a six.
He bounced back briefly with a birdie on the par-3 11th before giving away another shot on the 13th when he twice hit his ball through the green. He birdied the par-5 18th to at least finish a tough day on a positive note.
Scott said the wind was affecting the players' setup and shots.
"It really came up around the turn and blew hard on the back nine," Scott said. "It's really tough with the way it's blowing, you are trying to stay as stable as you can. It's certainly presented a pretty tough challenge this week."
Rumford said the course was on the "razor's edge" of toughness but said that is to be expected for a national championship.
The round of the day was a 67 by Australian Daniel Nisbet, who teed off in the first group Saturday morning before the wind picked up.