His Red Bull has looked the class of the field in pre-season testing, with Ferrari again its closest rival.
He told Formula1.com in an interview about the new season: "The winter period was pretty satisfying for us. We've managed to get good mileage under our belt - not as much as Ferrari - but more than we've ever done before.
"How good we are in the end compared to the others has a bigger question mark this season than any other season before.
"In previous years you had an idea of where you were and where the others were at the end of the test season, but this year it is almost impossible.
"There have been so-called experts coming forward offering their opinion but I don't think that anybody can realistically say what the pecking order will be in Melbourne, especially at the Albert Park track where we've seen surprises in the past.
"So let's wait and see. Within our team we are confident, so let's hope that we can stay that way."
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