SAO PAULO (AFP) - Lewis Hamilton admits that his high-speed life as Formula One world champion has left him exhausted.

But, he added, he was shaking off a fever that had delayed his flight from Europe and was looking forward to fighting for his first Brazilian Grand Prix victory this weekend.

Hamilton was expected in Sao Paulo on Wednesday to attend a news conference, but postponed his arrival until Thursday when he went to Interlagos for preparations with his Mercedes team.

He was quick to clarify that he did not suffer any injuries in his car crash in Monaco late on Monday night.

And he added that he was feeling much better after catching up on his sleep.

"I feel good. I'm on an up slope, so a lot closer to 100 per cent," he said before adding that he felt his busy lifestyle had caught up with him after he had returned to London from Mexico to throw a 60th birthday party for his mother.

"I'd gone to Mexico on Wednesday, worked Wednesday to the following Thursday, and then I had my mum's party," he said.

"It was pretty amazing, but I really felt it on Sunday and Monday. I slept a lot and feel a lot better for that.

"Now I'm excited to be here. And I'm glad there are still two races to go because the end of the season comes and you can't wait to get back in the car, so I'm definitely cherishing the moments I am in the car."

Hamilton denied he had lost any motivation to win races since clinching his third title triumph in last month's United States Grand Prix.

"I don't feel like the intensity has changed," he said.

"(Team-mate) Nico (Rosberg) is pushing and he doesn't want me to win, I don't want him to win, so that intensity stays the same, so you end up naturally staying in the same zone."