(CNN) -- Sebastian Vettel insists he's ready for anything as he looks to become the youngest triple champion in Formula One history
The German, who was second fastest in Friday's practice behind McLaren's Lewis Hamilton, is expecting unpredictable weather at Interlagos as he goes head-to-head with rival Fernando Alonso.
Red Bull's Vettel will take a 13 point lead over the Spaniard into the final race of the season and needs to secure a top four finish to win the title.
But the 25-year-old is wary of the weather with heavy storms forecasted for Saturday night and Sunday.
"It was very slippery for everyone, quite hot today and in terms of track conditions not that easy," Vettel told reporters.
"So everyone suffered the same kind of problems - track, stability and so on -- so we have to do our homework now no matter what the weather forecast says.
"We will see. It is a bit unknown what is going to come. So far we can be happy. We have to do our homework and improve the car, there is a lot still to come.
"Obviously we don't know what the weather is going to do. Today is incredibly hot, tomorrow is supposed to be hot with maybe some rain, and Sunday a bit cooler -- this is Sao Paulo so it could be anything."
Alonso finished fifth fastest in the morning session and sixth in the afternoon on the final practice day at Interlagos.
But the Ferrari man believes there is still work to be done going into Saturday's all-important qualifying session.
"It was very hot out on the circuit today and, especially this afternoon, the track temperatures were well above normal, even for this circuit," he told reporters.
"We have not yet found the ideal balance on the car, so there is still a lot of work to be done with the engineers going into the rest of the weekend.
"The predictions are for very different conditions from Saturday to Sunday, further reason to concentrate on the best choices when it comes to preparing the car for qualifying, but especially for the race.
"After so many Fridays, there is nothing much new to say about the tyres: the hards appear to be more consistent, while the mediums produce a quicker lap time.
"It's hard to say if we prefer rain or the dry: as I said before, it is vital to be prepared to tackle both situations.
"We know we have to score 14 points more than Vettel for the championship and not lose the same number to McLaren to maintain our second place in the constructors'.
"So we know our targets are clear, but also difficult to achieve."
After winning in Texas, Hamilton continued his good form by topping the time charts ahead of what will be his final race for McLaren.
The Briton clocked a fastest lap of one minute 14.026 seconds and will be confident of securing pole on Saturday.