Swiss rider Fabian Cancellara won a record fourth time trial title in a welcome diversion for a World Championships rocked by Alberto Contador's suspension due to a positive drug test.

The last rider out in a 42-man field, Cancellara charged through the 45.8 km circuit in the Melbourne suburb of Geelong in 58 minutes and 9.19 seconds to finish 1:02.75 seconds ahead of Briton David Millar.

Germany's Tony Martin took bronze despite suffering a flat tyre.

"It was maybe the hardest (world title) because before this time trial I didn't know actually where I am really standing," Cancellara, a late confirmation for the meeting, said in a televised interview.

"In the end I was focused on my own and tried to really do what I can, and that's (to) do a perfect ride. I think the tactic I did for this race was amazing and ... I'm happy."

The Swiss 29-year-old, one of just a handful of riders to break the hour-mark on an overcast, gusty day, saved himself on the first of the circuit's two laps, but powered away in the second and held up four fingers as he crossed the finishing line.

He had endured a nervous moment when he nearly clipped a barrier on a temporary bridge midway through his run but was otherwise a model of control.

"No, no, no, I didn't touch it," said Cancellara, whose victory put him ahead of triple world champion Michael Rogers of Australia and also made him the first rider to win a fifth medal in the world time trial. He also took a bronze in 2005.

"Every second counts. I'm trying really to be close but not that I want to fall in because that's the last thing that I want. I want to go through safe but that's my style of riding," he said.

The Swiss will compete in the men's road world championship on Sunday and will have a good understanding of the challenging circuit, whose near-kilometre climb to the finishing line proved taxing for riders on Thursday.

"I want a bit more to enjoy this (today)," he said. "Tomorrow morning when I wake up, then it's another day."

Millar, who was stripped of his 2003 world title and served a two-year ban for doping offences, was the first rider to break the hour-mark and briefly raised British hopes of a first men's champion since Chris Boardman won the inaugural world time trial in Catania, Spain, in 1994.

"My tactic was the opposite of Fabian's, which was to attack the first lap and then hang on for dear life, and that's basically what I did," the Malta-born Scot laughed.

"I'm over the moon with the ride. I came here hoping to get on the podium and that's what I did so it's a lovely feeling to actually achieve your objective."

Martin, a bronze medallist last year at Mendrisio, was gutted with the flat tyre that cost him precious momentum.

"It's always hard to keep the motivation when you have a flat tyre because every second is counting," he said.

Reuters