V8 Supercars driver Mark Winterbottom is confident his physical conditioning will overcome the detrimental effects of a virus he's battling this weekend in Darwin.

The Ford star says he feels a bit like an "ape in a zoo" as he finds himself in near-isolation away from his Falcon at Hidden Valley Raceway but he still battled his way to third place in Saturday's 120km race.

And despite facing the prospect of temperatures over 50 degrees inside his car for Sunday's 200km race in the Top End, Winterbottom is backing his hours in the gym to ensure he stays up the front.

"You train hard before the races to make sure that in a worst-case scenario, you will be right to battle," said Winterbottom, who is just 40 points behind championship leader Jamie Whincup after Saturday's race.

"I've got no doubts it'll be okay.

"It is hot. When you've got a virus, you run higher temps so you naturally feel hotter, sweat more, so it is more physical but the effort in the gym is what I'll rely on tomorrow to get through.

"Sunday night I'm sure I'll just fall in a heap but just got to get through tomorrow okay."

NZ Newswire