Felipe Massa says while Williams set about holding off Force India and McLaren, his new team also needs to chase down Ferrari.
Williams, powered by the Mercedes V6 engine, have made a stellar start to this season and are fourth in the Championship after nine races.
The team has scored 103 points, a staggering number when one considers that last year they managed just five. 15 of those points came through Valtteri Bottas' third place finish at the Austrian GP.
And although Massa is pleased with his team's progress, he has urged Williams to continue their fight against F1's heavy-weights such as Ferrari.
"We always need to think about getting better," Massa told GPUpdate.net.
"We have improved step-by-step. We haven't brought pieces that make the car completely different. We're doing a good job on the development.
"In the last three races we were stronger than Red Bull and Ferrari. So if we are better than them in terms of pace, why can't we fight with them?
"At the moment we are a few points behind Ferrari and a bit ahead of Force India and McLaren.
"We need to fight to stay ahead of them but also Ferrari - Red Bull is maybe a bit far but you never know."