For the first time in five years Red Bull won't enter a Formula One motor racing season as favourites.
Sebastian Vettel has won the last four titles, but the Renault-powered car has been beset by problems in preseason as the teams come to grips with changes to the cars including a shift from V8 engines to a 1.6 litre V6 turbo.
Red Bull team boss Christian Horner says he doesn't know how long it will take to solve the reliability problems that have blighted their pre-season.
The Formula One season opens in Melbourne on Sunday.
Many commentators are picking Lewis Hamilton to win with Mercedes this year.
