Rory McIlroy's hopes of retaining his Australian Open title look to have sunk without trace after a woeful third round left him well adrift of the leading pack.

Two 69s had left the world number one firmly in contention to defend the crown he won in thrilling style last year, but he has been some way short of his best in Sydney this week.

That was evident on Saturday as a 76 left him on one-over-par overall, six shots adrift of leading trio Brett Rumford, Jordan Spieth and Greg Chalmers, and five behind Adam Scott who is one off the lead.

Despite being level par after eight holes — when he was joint leader — with a bogey at the fourth immediately followed up by a birdie at the next, McIlroy’s round fell apart just before the turn.

He found the rough on the ninth and struggled to dig his way out en route to a triple bogey seven and he then made a double bogey six at the 10th to tumble down the leaderboard.

He birdied the next but another pair of bogeys, at the 13th and 16th, dropped him further back.

A birdie at the last meant the Northern Irishman at least ended on a positive note going into the final round, but the damage had long since been done.

McIlroy won the title at the Australian Golf Club 12 months ago on the 72nd hole, where he pipped world number three Adam Scott, who is currently one shot off the lead after his 69.

Although McIlroy was not ready to concede, he admitted he had given himself a mountain to climb.

“It was a tough day obviously,” he said on the tournament’s website. “The wind was up. I was doing okay, steady enough, until I got to the ninth. I hit a wayward tee-shot into what I thought was a decent enough lie that I could advance the ball.

“But I didn’t realise what I was standing on is not like dirt or earth. It was more like carpet. So the ball went underneath the carpet. Had it been a normal surface it would have been alright, but down there it was impossible.”

Even if retaining his title proves out of reach, McIlroy is keen to put on a show on Sunday in his final round of the year.

“I need a fast start tomorrow to have a chance,” he said. “It depends too on what the guys ahead of me do. I need some help. But the greens have been firmer every day. So a low score is higher than it was.

“I still feel like I can shoot a good one. I just don’t know if that will be enough. I’ll be trying my best. It’s the last round of the season so it would be nice to make it a good one.”