Mercedes driver Lewis Hamilton has admitted that he has his "work cut out" if he is to come out on top ahead of teammate Nico Rosberg this season.

Hamilton said that he has a good relationship with Rosberg since being teammates in their karting years and that he intends to up his game in order to win more points than the German.

"He's driving fantastically well," Hamilton told Sky Sports News. "He's definitely raised his game and so I definitely have my work cut out, but that's normal.

"We're just working as hard as we can at the moment. We've known each other for a long time, we've got a history like no other drivers here probably has - [we were karting] teammates in 2000 - and that relationship remains today."

Hamilton finished behind Rosberg in the Friday practice for the Chinese Grand Prix.