The Grand Prix season kicks off Down Under with, as Chief Sports Writer Scott Wilson reports, the sport desperately searching for Michael Schumacher's heir apparent .

IT isn't just a new Formula One season that will begin in Melbourne's Albert Park tomorrow, it is the start of a new motor racing era.

After 15 years of almost uninterrupted dominance of the sport, Michael Schumacher will not be on the grid for the opening race of the campaign.

His absence represents both a tremendous opportunity and potential for decline.

Opportunity, because after years of Formula One being little more than a one-man show, a sense of genuine competition has returned to the paddock.

But also a threat of decline, because whereas Schumacher was a sporting behemoth able to preach the Grand Prix gospel to the masses, it will take time for any of his successors to develop a similar sense of gravitas.

So while this season's championship is likely to be one of the most keenly-fought and competitive for a generation, the question the sport's authorities are likely to be asking themselves ahead of tomorrow's curtain raiser is 'will anyone notice?'

Formula One without Schumacher is like tennis without Roger Federer, or golf without Tiger Woods.

"It's the first time for 15 years that Michael hasn't been around," said his former championship rival, Damon Hill. "That's got to be interesting, hasn't it?"

Interesting, but also challenging. Uncertainty is all well and good, but eventually Formula One will need someone to assume Schumacher's mantle if it is to retain its place in the sporting consciousness.

Perhaps, after his back-to-back title triumphs, Fernando Alonso will be that man.

Amidst all of the eulogising that accompanied Schumacher's retirement, it was easy to forget that Alonso had dethroned him in successive campaigns.

The Spaniard has not been afforded the credit he deserves, but just as he seemed poised to stamp his authority on the sport with a hat-trick of title wins, he undermined his position by putting money before success.

Alonso's surprise decision to swap Renault for McClaren is hardly the act of a man obsessed by building a legacy.

True, Ron Dennis' team have a history of success that encompasses such luminaries as Alain Prost, Ayrton Senna and Mika Hakkinen, and the quality of their pre-season testing suggests they will hit the ground running in Australia this weekend.

But after McClaren failed to win a single Grand Prix last season, nothing should be taken for granted.

The decision to appoint rookie Lewis Hamilton as Alonso's junior partner is a considerable gamble and, while the MP4-22 is fast, it is yet to prove that it is more reliable than its error-prone predecessor.

When it comes to reliability, Ferrari remains the team to catch. The sport's leading marque rarely lets its drivers down, although the departure of former technical director Ross Brawn could yet prove as significant as Schumacher's retirement.

Brawn was the nuts and bolts behind Ferrari's recent dominance and the absence of his expertise, allied to the loss of Schumacher's legendary dedication to testing and technical development, has left the Tifosi in a position of unusual vulnerability.

Despite winning two Grand Prix, Felipe Massa is yet to prove he has the skills to match his exalted reputation, while for all of his qualities behind the wheel, Kimi Raikkonen is as laid-back as Schumacher was driven.

The Finn is expected to be the dominant partner in the relationship but, if Massa can reproduce the form he has shown in winter testing in the first half of the season, Raikkonen could be relegated to a support slot by the time the Grand Prix circus rolls into Silverstone in July.

The same could be true of Giancarlo Fisichella, expected to spearhead Renault's assault on a fourth constructors' title, but arguably no better than his rookie team-mate Heikki Kovalainen.

Renault's decision to keep faith with Fisichella is commendable, but a record of just three wins from 178 Grand Prix suggests the Italian is hardly a champion in waiting.

Kovalainen, on the other hand, is poised to become the season's surprise package.

In December 2004, the 25-year-old Finn beat Schumacher to win the Race of Champions, an end-of-season shoot-out between title winners from across the motor sport spectrum.

He has finished second in the GP2 series, and knows his Renault inside out after doing much of the donkey work for Alonso and Fisichella last season.

Kovalainen is unlikely to win the drivers' title this year, but he will almost certainly win the Grand Prix and, unless he keeps pace with his team-mate, Fisichella could find himself unceremoniously dumped for Nelson Piquet Junior before the season comes to an end.

With question marks hanging over all three of the leading teams, could this be the season when Honda finally provide Jenson Button with a platform from which he can launch a tilt at the title?

It is now seven years since the Englishman made his Formula One debut and, while last season's maiden Grand Prix win proved that progress had been made, the 27-year-old should really have achieved more than he has.

Honda's overall lack of competitiveness did not help his cause last season and Button must be hoping that the company's decision to dedicate the paintwork on their car to an ecological theme is not a sign of things to come.

In the past, Honda have tended to cut down on emissions by failing to produce a V8 engine that is able to power their car to the finish.

Pre-season testing has not gone well, and both BMW and Williams will be hoping to overtake their Japanese competitor this season.

If BMW can find some reliability to accompany their undoubted speed, Pole Robert Kubica could build on an impressive debut last year, while Williams, having switched to Toyota engines, are confident of giving Nico Rosberg an opportunity to record his first Grand Prix win.

A maiden victory might be too much to ask for Britain's two rookies - Hamilton, who will have to cope with the pressure of being the first mixed-race driver to compete in the sport, and Anthony Davidson, who will surely be handicapped by Super Aguri's lack of Formula One expertise.

David Coulthard completes the British contingent, and while Red Bull remain the mavericks of the paddock, this could be the season when Christian Horner's team starts to make progress on the track.

Technologically, the biggest change this season stems from the withdrawal of Michelin, meaning that Bridgestone has become the sole supplier of tyres.

But the loss of a tyre company is nothing compared with the absence of Schumacher. Commentators once claimed the German was slowly killing Formula One. Now the primary challenge will be to prove the sport can survive without him.