Sebastian Vettel says there is still "a lot" to come from Red Bull as the German bids to be crowned F1's youngest triple World Champion.
The German is the favourite to secure the Drivers' title this weekend in Brazil as he holds a 13-point advantage over Fernando Alonso in the standings. And he's driving one of the best cars in the field.
That was apparent yet again on Friday when Vettel finished second in the practice sessions at the Interlagos circuit, bringing his RB8 home in 0.274s adrift of Lewis Hamilton's best.
Asked whether he was confident about his chances this weekend, the 25-year-old said: "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."
Vettel, though, is confident that even if the rain were to come down it would not negate Friday's work.
"Nowadays we don't really have a wet set-up anymore, there are a couple of things you would like to change if it is really wet, but if it is not that wet then we will just put on the wet tyres and go from there," Vettel told Sky Sports F1.