Ferrari driver Sebastian Vettel retains hope he can win the Formula One title despite his recent woes.
The German has fallen 59 points behind Lewis Hamilton in the drivers' standings after reliability issues late in the season.
With just four races remaining this campaign, beginning with the United States Grand Prix this weekend, Vettel looks to be too far back to win the title.
However, the four-time champion still believes in his chances of overhauling Hamilton.
"I still think we have a chance and we only have to stay focused on our job," Vettel said.
"We have a great car and a good package, which could have won the last two races; we didn't, but this doesn't mean we don't have a chance to win the last races. So, we need to look at what's next and focus on the next events.
"Overall, I think it's been a very good season for us so far. Some people will base their judgement on the last couple of races, which were not so good, but I think we are the team that improved the most this year. Probably nobody expected us to be as strong as we have been.
"So, I think there are many positive aspects. We still have races ahead of us and a strong car and we keep improving. We are going in the right direction and we have clever people on board. So I don't look at what is already behind us, and I stay focused on what's ahead of us."
Hamilton has been dominant in Austin in recent years, winning the past three - and four of the last five - races in USA.
Vettel is unsure what to expect in Texas, but he is upbeat about Ferrari's chances.
"As for this weekend, I honestly don't know what to expect here, but the track is 'mixed' and the speed is there, so I am optimistic," he said.