Defending Formula 1 World Champion Lewis Hamilton has suggested that all the usual front-runners will again be making the running in the Australian Grand Prix except for McLaren-Mercedes - rating his current challenger only four-out-of-ten and intimating that winning the title last year has potentially harmed the team's chances in 2009.

The Woking-based outfit's MP4-24 has proven to be consistently off the pace in pre-season testing, frequently languishing down towards the bottom of the pecking order on the timesheets as it battles aerodynamic woes related to the new rear wing. Hamilton admitted that he is in for a 'challenging' season, with a solution unlikely to be found until 'four or five' races in.

"We'll have pretty much the same people up there as last year, except for us obviously," the British star - bidding to become the first of his countrymen to successfully retain his crown in the 59-year history of the top flight - is quoted as having said by the Associated Press in Melbourne ahead of this weekend's curtain-raiser.

"It (world champion) is a great accolade to have, a great title to have next to your name. I've reset the targets again. I want to be world champion again, although it will be tough this year.

"We don't know what to expect this weekend. It will be a real challenge for everyone, so much has changed. It doesn't only affect drivers, but the teams. People will be making adaptations and getting used to it."

That is a reference to the sweeping changes that have been introduced in 2009 - from the pioneering KERS (Kinetic Energy Recovery Systems) technology to the return of slick tyres and dramatically altered front and rear wings - and Hamilton argues that in pushing so hard to clinch the laurels last year, McLaren disadvantaged itself for the forthcoming season by enabling its rivals to gain a handle on the new rules significantly earlier.

"I think we focused so much on last year's car [that] we maybe left it a little bit late to focus on this year's car," reflected the sport's youngest-ever world champion and the 2008 Australian Grand Prix winner. "It's difficult to say, but people have obviously done a better job at the moment."

Despite rating the new machine as a mere four-out-of-ten - compared to eight for its predecessor, the MP4-23 - the 24-year-old added that he was confident that McLaren possesses the necessary talent and facilities to rapidly play catch-up, even if his initial objectives have had to be somewhat revised.

"Last year's car, in marks out of ten, I'd probably give an eight," the Stevenage-born ace contended. "This year's at the moment would be a four, [but] we've got a fantastic team and the guys are working flat-out to recover the situation and bring it back to the top.

"Who knows? This weekend we've got lots of bits coming, so hopefully we can try and fight at least for some points. I think over the course of the next four or five races, that's where we'll see the major improvements and hopefully get back to the front. It will be challenging."