Mercedes Formula One driver Lewis Hamilton of Britain talks to journalists during pre-season testing at the Jerez racetrack in southern Spain February 4, 2015. Photo by Marcelo del Pozo, Reuters.

LONDON - Lewis Hamilton starts the Formula One season as red-hot favorite to become a triple world champion but Niki Lauda, who knows how that feels, fears the battle could be tougher than ever.

The Briton won 11 races to Mercedes team mate Nico Rosberg's five last year, with Red Bull's Daniel Ricciardo taking the other three, and heads for the season-opening Australian Grand Prix in Melbourne on March 15 with every reason to be confident.

The 'Silver Arrows' have been ominous in testing, lapping with metronomic efficiency and eye-openingly faster than anyone else once they finally got around to bolting on the quicker soft tyres.

"Expectations are enormously high because we won everything that we could win last year," triple champion Lauda, now non-executive chairman of the Mercedes works team, told Reuters in an interview.

"The logic is that everybody expects and wants to have the same thing (again) but I can tell you it is not that easy. A new season is a new season and everything starts from scratch.

"I think Lewis and Nico will fight again like always for the championship but my worry is there will be a third guy also getting involved, no question."

Who that man turns out to be remains an open question, although Finland's Valtteri Bottas may be a shrewd bet after Williams looked closest to Mercedes in testing.

The ever-smiling Ricciardo, now Red Bull's team leader following the departure of four times champion Sebastian Vettel to Ferrari, looks another solid candidate to take the fight to Mercedes.

"At the moment I would say that Williams is the closest, Red Bull and Ferrari I cannot tell you now because they had some signs of speed and then nothing happens again. Red Bull you can never under-estimate," said Lauda.

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Hamilton hot favorite for triple triumph