Lewis Hamilton believes new Formula 1 cars will be a 'massive challenge' - BBC

Lewis Hamilton says he believes the new faster Formula 1 cars this year will be a "massive challenge".
The Mercedes driver said he had trained hard but had no idea whether he was fit enough for cars which could be four seconds a lap faster than 2016.

"I don't know if I'll be easily fit enough, or will struggle a bit or be super-underneath and need to work harder," the 32-year-old said.

While confident, he said he did not know if Mercedes would remain in front.

The three-time world champion, in an exclusive interview with BBC Radio 5 live, added that he:

*was over losing the title to team-mate Nico Rosberg last year

*looked forward to the challenge of his new partner Valtteri Bottas

*was concerned some aspects of the new rules might not work

*believed Red Bull's form was the one to watch before the start of pre-season testing

*hoped new F1 owners Liberty Media would implement changes to make the sport more exciting'