Senna confident he can still save his seat at Williams for 2013

The 29-year old Brazilian is under pressure to keep his drive, with speculation mounting that he will be replaced by the team's reserve driver Valtteri Bottas next year.

But Senna reckons he still has a chance if he manages to make himself "indispensable" in the last four races of the season.

"If you start dwelling over not being sorted for the following year then you start putting too much pressure on your driving and then things don't flow so well," said Senna when asked what he needed to achieve by AUTOSPORT.

"For me the focus is to make sure I make myself indispensable and race as well as I can.

"It's not about [improving] one thing or a [one-off] result," he added. "It's always lots of things.

"If you take any doubts that the team has about you away, so instead of having one good result here and another there, but instead put these performances together then these guys think; 'Okay, it just takes a few factors together for it to happen'."

Senna has been vocal about his loss of running time on Fridays, with Bottas having driven his car in 12 Friday practice sessions this year, and admitted that it had hurt him in race weekends more than he'd expected.

"I never expected it to be so tough without the first session because until it happens to you, you don't really understand how much it causes trouble," he said.

"But for sure it's not like I had much choice. I had to take that, driving for Williams was a good bet for me and I took that risk.

"For sure nowadays I have a different perspective on giving away basically all my Fridays for the year to someone else because if you have one little problem after that, that's it pretty much, it's the weekend over."

Senna added that this year, with car performance being so close, even subtle track evolution understanding can be critical.

"It is difficult to jump into a session where the track has moved already and try to understand what direction the track is moving in, in terms of car balance, speed in each corner, where the track is rubbering in and therefore how you develop the car set-up," he explained.

"Sometimes we found ourselves in FP3 with a very good performance, but then the track changed a little bit for qualifying and the people with more mileage just knew that was going to happen on the track in qualifying, so they did a little tweak in the set-up to compensate."

Senna indicated that he had spoken to Williams about this and has made it clear that he would not want a similar situation in 2013.

"For sure this has been an ongoing subject throughout the year between myself and the team regarding missing so many Fridays," he said. "They really understand that it has put a big dent on my performance for some of the weekends. The teams knows how well I have been doing in the races."

Senna is only seven points behind Spanish Grand Prix winner Maldonado in the championship, and said that a key objective is to finish ahead of the Venezuelan in the standings.

"For sure if you score more points than the other guy then it becomes very difficult for the team to start thinking about someone else, but Formula 1 is Formula 1 and lots of things can happen.

"But there are still four races to go, lot's more points on the table and hopefully we can get very near him, or in front."