Mercedes admits pressure to deliver an F1 championship assault

The German car manufacturer won three races last year as Lewis Hamilton and Nico Rosberg helped guide it to second place in the constructors' championship.

And it is that level of progress - ahead of a major rules overhaul that is set to favour the works teams - that has left its bosses expecting even more in 2014.

Wolff, who is now running the team with Paddy Lowe following Ross Brawn's decision to step down, concedes that the Brackley-based squad must not do worse than it did last year.

"No, we cannot afford that," said Wolff in an exclusive interview with AUTOSPORT.

"If we had finished fourth or third, people could say there will be an evolution before being world champion.

"But now the expectations are very high, and we have to manage those expectations because winning a world championship is not an easy task. It is very difficult.

"It is different to winning races because you have to put everything together. But can we honestly say that we are a contender for the world championship? No."

Wolff thinks it vital that Mercedes must not let itself get either too bullish or too downbeat about its prospects, as both approaches could hurt it.

"Optimism is always dangerous," he said. "You have to be a pessimistic optimist.

"The general tendency has to be pessimistic. You have to not take it for granted that it is going to happen. But also you must not make your life bad by being too pessimistic.

"What I can see is the effort, intelligence and resource being put into the engine development and powertrain development - and I believe that the right things are being done.

"Now do I know what Ferrari and Renault are doing? No. I am sure they have intelligent people and they are doing good work there as well. It is all crystal-ball reading."

Although paddock speculation has pointed to Mercedes starting the season with the best engine, Wolff is not so convinced that matters will be so clear cut.

"We don't know. It is all based on rumours and gossip, and can you fundamentally rely and make an opinion on what A has said to B, when probably both of them have no clue!

"I remember from Viry, and from I have seen at Maranello, that these guys are no fools. They are very intelligent people working very hard and I doubt one engine manufacturer is going to have a massive advantage."