Five biggest questions as Formula One season begins

Sunday marks the start of nine months of high-octane Formula One action, beginning Down Under with the Australian Grand Prix in Melbourne. What the five burning issues that will be answered in this F1 season?

1. Can we call Lewis Hamilton an F1 great?

For years, he was hailed as the next great talent after Michael Schumacher, destined to become a serial-winning champion just like the German. but after clinching his first F1 drivers' title in 2007, he failed to build upon that success, letting the like of Jenson Button and Sebastian Vettel trump him for titles.

Talks began to surface that the Briton is squandering his considerable talents with his celebrity, jet-setting lifestyle. However, Hamilton proved that the desire was still there as he out-duelled his Mercedes team-mate Nico Rosberg to win last year's F1 title in thrilling fashion.

Now Hamilton must prove that he deserves to be mentioned among the F1 greats, and the best way possible to do so is to win the drivers' title again. He has a great car, but his rivals - Rosberg, Vettel, Kimi Raikkonen and Daniel Ricciardo - are all eager to catch up and beat him to the title.

Can he fend them off? This will be the top storyline going into this new F1 season.

2. Who are Mercedes' key challengers?

While Mercedes are still favourites to retain their constructors' championship, they will face much stiffer competition than last season's easy stroll to the title. Three teams - Williams, Red Bull and Ferrari - have their eyes set on toppling Mercedes from their perch.

Williams have had a very quiet, but a productive winter. Red Bull have been a "mixed bag" in pre-season testing with decent times and not so encouraging reliability. However, the surprise of the year might be Ferrari.

The Scuderia look confident under new hierarchy and going by test-times, they have once again produced a quick car. Also, another thing which we all should look forward to is how Vettel will gel in with a Ferrari.

It makes for an interesting battle at the top of the F1 competition.

3. Will there be more danger at the bottom of F1?

The demise of Marussia and Caterham last season due to financial trouble highlighted the high cost of running F1 teams. Life at the bottom of the F1 table is no walk in the park; besides the two defunct teams, teams like Force India, Lotus and Sauber are also walking the tight-rope.

F1 supremo Bernie Ecclestone has promised earlier this month to bring forward prize-money payments to the struggling teams. Yet the problem lingers: is F1 far too expensive nowadays to compete in? Things may look really bleak if sponsors continue to back away from the small teams.

4. Will there be safety issues in F1 this season?

Unfortunately, the dangers of F1 racing were thrust back into the spotlight last season, with Jules Bianchi's crash at the Japanese Grand Prix which resulted in a diffuse axonal injury that continues to keep him in a coma.

There have been further safety concerns following Fernando Alonso's pre-season testing crash in Barcelona, which has forced the two-time champion to sit out the Australian GP.

A number of changes have been made for this season, including the introduction of a virtual safety car. Several races, including this weekend's and the Suzuka event where the accident occurred, will be held one hour earlier.

5. Can the young drivers make a name for themselves this season?

Toro Rosso's Max Verstappen will become the youngest F1 driver this weekend when he lines up on the grid on Sunday at the age of 17, smashing Jaime Alguersuari's record by nearly two years.

But the Belgian, son of ex-F1 pilot Jos, is not the only young competitor in Melbourne. Team-mate Carlos Sainz, also making his debut for Toro Rosso, is just 20, the same age as Red Bull's new Russian signing Daniil Kyvat. Sauber's Felipe Nasr is 22, as are both Will Stevens and Roberto Mehri, the young hopes for new outfit Manor Marussia.

Can any of these youngsters make an instant impression in the unforgiving F1 competition? Well, Vettel won his first F1 title when he was 23 years old. That's the record for these upstarts to chase.