Lewis Hamilton thinks McLaren could have the edge going into the rest of the Brazilian Grand Prix weekend after topping both Friday practice sessions at Interlagos.
While Formula 1 championship leader Sebastian Vettel was just 0.009 seconds behind Hamilton in the morning, later on the McLaren driver was able to go 0.274s clear of the Red Bull.
Hamilton, who will leave McLaren for Mercedes after this event, felt his Red Bull-beating pace in practice was a realistic reflection of form.
"The single-lap pace was really good. I struggled a little bit on the primes, but on the options I was able to get a very good lap out and at the time it was eight-tenths faster than anyone else," he said.
"Obviously everyone closed the gap towards the end. Sebastian had several tenths and I think he would have got close, but it didn't look like he could match the times, so that's a positive for us.
"But again, we'll see what happens with the fuel loads tomorrow. Qualifying is a different case, but I think we are definitely there or thereabouts this weekend.
"The long runs are the hardest part on the tyres which Red Bull has generally been good at, but we seem quicker than them on the long runs, at least quicker than [Mark] Webber."
Jenson Button was only eighth quickest in the second McLaren as he experimented with a lower-downforce wing.
Though he felt this was "interesting" set-up research, Button admitted that it seemed a less competitive option.
"It's less downforce but it works in a different way," he said. It's the worst conditions to run a low-downforce car, because in such high temperatures you overheat and slide the tyres.
"Surprisingly on the long run it's not that bad. It's just on the short runs where you can't use DRS where you'd like, because you haven't got enough grip."