Mercedes will not totally dominate 2015 - Lauda

Niki Lauda has played down suggestions Mercedes' dominance will be stronger than ever in 2015.

The German team utterly dominated the first year of the new 'power unit' era last season, winning all but three of the Grands Prix.

But despite the new W06 seeming unbeatable in the wake of the pre-season tests in Spain, team chairman Niki Lauda thinks rivals are ready to pounce.

"This will be a really interesting season that is not just about Mercedes," he told the Austrian news agency APA.

Lauda added: "The drivers' championship will probably not be decided solely between Lewis and Nico. A third or fourth one will be in the fight."

He said assumptions based on winter testing alone are rarely true in F1.

"I believe only the things that I will see in Melbourne," said Lauda, although he admitted that Mercedes is "well prepared" for 2015.

Who will challenge?

Last year, it was Red Bull's Daniel Ricciardo who put up the biggest challenge to the might of Mercedes.

In 2015, it could be Williams' Valtteri Bottas, although the Finn insists that Mercedes' advantage seems too big for now.

"It seems that they are at least half a second above everyone else," he told the Finnish broadcaster MTV3, "which is a harsh fact at this stage of the season."

Another potential Mercedes challenger has emerged in the form of Ferrari.

"It's going well for them," Lauda admits, "while for McLaren, the opposite is true. But that can change quickly."