Williams could finish second in this year's Formula 1 constructors' championship, says Felipe Massa.
The team are much improved after a miserable 2013 following their decision to run the dominant Mercedes engine.
While the works Mercedes team are way out in front, Massa believes they can catch current second-placed team Red Bull, who are 84 points clear.
"We need to fight for that. If we do a perfect job from now until the last race, it can be possible," said Massa.
Massa says Williams can even challenge championship leaders Mercedes in individual races once the season restarts at Spa in Belgium on 22 August - a race live across BBC TV, radio & online.
The Williams has been one of the strongest cars on faster, lower downforce circuits in 2014, thanks to the way the car is designed and the Mercedes engine.
"It's not impossible that we will have more of a chance against Mercedes.
"Spa and Monza should suit us, maybe Austin and Brazil, and in the last race in Abu Dhabi there are some good straights."
|Allan McNish, BBC F1 analyst:|
|"Williams are also now getting the best out of the car they have. They had some difficulties early in the season with excessive tyre wear in races but they went away and thought about it and sorted it out."|
|Read more in 'F1's winners and losers'|
Brazilian Massa, 33, is in his first season with Williams after leaving Ferrari - who are one place clear of his new team in third in the constructors' championship - and has scored 40 points so far, with his Finnish team-mate Valtteri Bottas registering 95.