Red Bull's Sebastian Vettel is champing at the bit to get his Formula One title defence underway at Sunday's Australian Grand Prix after a two-week delay to the start of the season that has frustrated drivers and fans alike.

The gloves will finally come off in Melbourne this weekend after the Albert Park race was restored to the place it once held as the season-opener when civil unrest forced the postponement of the March 13 Bahrain Grand Prix.

Vettel will begin the week as favorite after Red Bull went well in preseason testing but, with four former world champions also on the grid, the 23-year-old German knows his 2010 triumph will mean nothing when the racing starts again on Sunday.

"It's nice to look back at last year and at what we achieved, but we're all looking forward now and focusing on the new car and the new season," Vettel said in a team release.

"It all starts from zero again, we're excited, we've had enough of testing and we want to go racing again."

Fernando Alonso, champion in 2005 and 2006 and second behind Vettel in the title race last year, is expected to present the strongest challenge of the former world champions with the new Ferrari looking quick and reliable in testing.

"Overall, I think we will arrive in Melbourne in a 100 percent state of readiness, but whether or not that will be enough to win, we will not know until we are there," the Spaniard, who is partnered by Brazilian Felipe Massa, told the Italian team's website.

"I feel confident, just as I did last year going into the start of the season. We are in good shape, even if we know we are not racing alone out there."

Alonso prompted derision when he tipped seven-time champion Michael Schumacher to be a challenger in 2011, but a strong showing by the German and his compatriot and Mercedes teammate Nico Rosberg in testing vindicated his remarks.

Schumacher, now 42, had a season to forget on his return after three years of retirement but is clearly still enjoying life back in the sport and relishing the chance to return to Melbourne, where he has won four times.

"It is the atmosphere which makes Albert Park so special, and when you see all of the fans having fun, that just gives you a great feeling of how motorsport can be ... we are well prepared," said Schumacher, who made his F1 debut 20 years ago.

Britons Lewis Hamilton and Jenson Button, the 2008 and 2009 champions respectively, look to have a tough task on their hands to launch a credible challenge for perennial powerhouse McLaren in the season opener.

"We can't hide the fact that testing has been tougher than we expected," said Hamilton. "Our test mileage hasn't been as high as that of our rivals, nor have we had the outright pace of the fastest cars ... its felt like a very long winter."

"Dramatic" changes

The delay to the start of the season has at least allowed McLaren time to make some "dramatic" changes to their cars, making alterations to the floor and replacing the exhaust system with a new and simpler design that should prove more reliable.

Button will be hoping the unpredictability of early season races will be compounded by the raft of rule changes, and perhaps even a little rain, to give him at least a fighting chance of claiming a third successive Australian Grand Prix win.

The arrival of a new tire provider in Pirelli will add to the unpredictability with the 12 teams expected to make many more pit stops over the course of the race.