World Road Championships
Venue: Melbourne Dates: 29 Sept - 3 Oct Coverage: Live on BBC Red Button & online on 29 Sep (0600-0750), 30 Sep (0400-0835), 2 Oct (0400-0735, 2240-0610 - 3 Oct), 3 Oct (Highlights 1300-1400)
Cavendish recently won the green jersey at the Vuelta a Espaņa,
Mark Cavendish has all but written off his hopes of becoming world road race champion after testing out the course.
The Manx rider is in Australia ahead of Sunday's 262.7km race and admitted the Geelong circuit, which features two steep climbs, was "too difficult".
Cavendish said: "According to what people had been telling me beforehand, the rainbow jersey [awarded to the winner] was a possibility.
"Now I've been able to check it out, I'll have to revise my ambitions."
Sprint specialist Cavendish, 25, comes into the race on the back of a fine performance in La Vuelta earlier this month, where he won the Tour of Spain green points jersey, after three stage victories.
He also performed well in the Tour de France following a slow start, and had high hopes of doing well in Australia, telling the Sunday Independent last week: "I'm not going into it thinking 'I'm going to win this'... but there's a chance."
But after training on the 15.9km circuit for the past two days, Cavendish concedes he is unlikely to become the first Briton since Tom Simpson in 1965 to wear the coveted rainbow jersey, because the slopes do not suit his style.
He told Belgian broadcaster RBTF: "The course is certainly too difficult for me. I hadn't seen the circuit myself before now."
Sunday's race begins in Melbourne before heading to Geelong, where the circuit will be raced 11 times by the peloton.
Cavendish, who rides for HTC-Columbia, could still find it tough-going in the event of a bunch sprint, with the home straight rising steadily uphill for around 700m before the finishing line.
The cyclist plans to head to India to represent the Isle of Man in the Commonwealth Games after his participation in Australia.