Five talking points ahead of Australian Grand Prix
Pre-season testing suggests Mercedes will run away with the title once again, and if so the biggest question will be whether Lewis Hamilton or Nico Rosberg wins the drivers' crown.
Relations were strained to breaking point during their season-long battle last year before Hamilton clinched it in the final race.
With Mercedes indicating they'll let the Briton and the German settle differences by themselves, expect fireworks at some point in the season.
McLaren's pre-season could hardly have been worse and they find themselves without their new driver and with questions swirling at the opening race.
As if the MP4-30's performance in testing wasn't bad enough, Alonso's crash and concussion in Barcelona has ruled him out of Melbourne.
The nature of the accident also left several observers scratching their heads and prompted an investigation by world body the FIA.
"Very strange," was the verdict of Alonso's manager, Flavio Briatore.
Formula One had the 'Spygate' espionage controversy in 2007, and now 'Seatgate' is unsettling Sauber in the run-up to this year's first race.
Former reserve Giedo van der Garde won a court ruling ordering Sauber to let him drive in Melbourne, after he claimed the team reneged on a deal.
The Swiss team, which prefers the heavily sponsored Felipe Nasr and Marcus Ericsson, claimed it would be dangerous to let van der Garde drive an unfamiliar car and lodged an 11th-hour appeal, to be heard Thursday, after the verdict was announced on Wednesday.
Max Verstappen will smash Jaime Alguersuari's record by nearly two years when he becomes Formula One's youngest driver aged 17 years and 166 days on Sunday.
But Verstappen, son of ex-F1 pilot Jos, is not the only young competitor in Melbourne.
Team-mate Carlos Sainz junior, 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.
Vettel at Ferrari
The German was accused of switching fans off in droves during his march to four straight world titles, but he faced problems of a different sort last year when he wound up fifth, some distance behind Red Bull team-mate Daniel Ricciardo.
Now Vettel will look to emulate his hero Michael Schumacher by rejuvenating Ferrari, who are without a world title since 2008 and are under reconstruction as they start the season with their second new team principal in less than a year, Maurizio Arrivabene.
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