Former world champion Nico Rosberg has knocked down suggestions that Max Verstappen is a better driver than Lewis Hamilton and insisted that his old Mercedes rival will finish as Formula One's greatest of all time. Verstappen could prove to be Hamilton's closest challenger for a record-equalling seventh world crown when the new season gets under way in Melbourne on Sunday. The Red Bull driver, still just 22, is this season set to embark on what will be his sixth campaign in the sport. Remarkably, Hamilton was the same age as Verstappen is now when he started out 13 years ago. Indeed, Verstappen will become F1's youngest world champion if he beats Hamilton to this year's crown. The Dutchman finished third in the standings last season and won three times in largely inferior Red Bull machinery, passing Hamilton twice to win at the penultimate round in Brazil. But Rosberg – the only man to have stopped Hamilton from winning the title in the last five seasons – says it is too premature to rank the rising Red Bull star ahead of his former foe. "Max is the one guy in F1 who is on a similar level to Lewis," 2016 world champion Rosberg said. "He has that very rare exceptional talent that Lewis has – a once-in-a-generation talent – and if he has the right car, there is no question he will be a contender for the championship this season. "But you cannot say that Max is a better driver than Lewis. Lewis is going on to become the best of all time, so you cannot say that at all. "Lewis is the absolute favourite to win the championship – but I have really high hopes that we can be in for a thrilling season. "I am confident and optimistic that Red Bull and Ferrari can up their game and be on a level playing field with Mercedes." Hamilton and the rest of the F1 circus have arrived in Melbourne for the traditional curtain raiser which will go ahead as planned despite the postponement of several sporting events due to the coronavirus outbreak. The Bahrain Grand Prix, which is scheduled for the weekend after Melbourne, will take place behind closed doors. Officials for the Vietnamese Grand Prix – set for April 5 – are ready to push ahead with their inaugural race. F1 meanwhile has announced a major new sponsorship contract with Saudi oil company Aramco. It marks the first significant partnership deal of American owners Liberty Media's three-year tenure and is set to pave the way for a race to be staged in Saudi Arabia in the coming years.