Niki Lauda has rubbished suggestions the private lives of Mercedes\' race drivers could affect their championship hopes in 2015.World champion Hamilton has broken up with his long-time girlfriend Nico

Niki Lauda has rubbished suggestions the private lives of Mercedes' race drivers could affect their championship hopes in 2015.

World champion Hamilton has broken up with his long-time girlfriend Nicole Scherzinger, while the newly-married Nico Rosberg's wife is expecting their first child.

"It has absolutely no influence," Mercedes team chairman and F1 legend Lauda told the German newspaper Bild am Sonntag.

"The story that you slow down when your wife is pregnant is complete nonsense," he said. "Formula one drivers are true professionals who want nothing else than to win. It's what they are paid for."

As for the heart-on-the-sleeve Hamilton's personal life, Lauda explained: "I have talked to Lewis about it.

"Whether he has brought his private life in order or not is very much overrated by journalists," said the triple world champion. "Lewis simply gets in the car and does his job."

Part of Hamilton's job at present is to personally negotiate a new contract, but Lauda denied that the protracted talks have stalled and might fail altogether.

"Not at all," said the great Austrian. "Everything is very relaxed.

"He negotiates very well, and we do too. Lewis will be with us in 2016, definitely."

Mercedes kicked off its 2015 campaign in utterly dominant style on Sunday, but team boss Toto Wolff vowed to keep his feet on the ground.

"From the pure performance of the car," he told German television, "we are probably in a separate category but Ferrari showed today that they have made a big leap.

"They have all the resources and the people to be able to keep improving," added Wolff.

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