"I'm confident," he is quoted as saying by the BBC. "We will fight to the end. We are not fast enough, this is true and we know this.
"It's a weak point, the performance that we have at the moment in our package, but we have some strong points which we will try to use.
"We have two important races. We will try to finish in front of Sebastian. We know that maybe with pure pace we cannot do it; we need to use other points."
The next Grand Prix is in Austin, Texas on November 18 and the final race will be held in Brazil a week later.