Felipe Massa: Williams F1 team can't afford any imperfections

Williams has often been best of the rest behind the dominant Mercedes cars during the 2014 F1 season and targeted a three-four result at last Sunday's Austin race after locking out the second row of the grid.

But both drivers were undone by a charging drive by Daniel Ricciardo and sharper strategy from his Red Bull team so finished a disappointing fourth and fifth.

Massa, who lost crucial time to Ricciardo at his final pitstop in the US GP, reckons Williams needs to be totally on its game at all times if it wants to regularly beat teams with world championship-winning pedigree, such as Red Bull.

"We had so many lost opportunities this year," Massa said.

"We are fighting with the top teams, so if you don't do everything perfect you lose a position.

"There's still some organisation we need to improve.

"We need to analyse things better, we need to be more complete.

"I'm not saying we are doing a horrible job, but we were talking about one or two seconds [lost in the pits] and you are fighting with a team that won the last four championships, so it's enough to lose a position.

"We did a good job, but not a perfect job, and when you're fighting with a top team you need to do a perfect job in whatever situation.

"It's a team that is growing and improving and we know there is still a long line to be perfect."