Felipe Massa believes Williams needs to make a 'triple' effort this winter if it is going to be able to catch Mercedes and Ferrari.
Having clinched third place in the constructors' championship at the Brazilian Grand Prix, Massa says that Williams has been left wanting much more after not quite living up to its lofty pre-season expectations.
"For sure we always want more," explained the Brazilian. "I expected maybe to be fighting for second place in the constructors' championship, and it was not possible.
"Ferrari were a bit too quick, they made big improvements compared to the other teams apart from Mercedes, who are far away in front.
"We did a good season to finish third in the championship, but I remember last year we celebrated massively to finish third in the end. Now we were third in the championship with a good gap – so I think it was definitely a good season.
"But we want more, and we are pushing so hard to see if we can make a triple improvement for next year - which is the only way to catch the guys in front."
As well as eyeing progress for next year, Massa believes that the big rules overhaul for 2017 – with cars set to be five-seconds per lap quicker – could offer Williams a big opportunity to become more competitive.
"I think the regulation change will be a big change for everybody," he said. "We made a big improvement when we had the last regulation change, so maybe yes [we can do it again].
"But it is too early to say that. We need more time, we need to understand the regulations first and see what is working from team to team."
Interview by Valentin Khorounzhiy