After a solid start to the Belgian GP weekend, Felipe Massa believes Williams will be involved in the podium battle come Sunday.
The Brazilian finished fourth quickest in Friday's second practice at the Spa-Francorchamps circuit while his team-mate Valtteri Bottas was sixth.
The duo were 1.1 and 1.4s off the pace set by Mercedes' Lewis Hamilton.
"It was a good Friday for us with no issues and we were able to continue learning about the car," said Massa.
"We saw some tyre degradation so that will make tyre strategy crucial and it will be important to be on the right tyre at the right time in the race.:"
However, looking at the timesheets, he admits it going to be difficult to beat the Mercedes drivers but that doesn't mean Williams can't join them on the podium.
"Mercedes are still looking very strong and seem to have an advantage over everyone else," he said.
"But," he added, "we should have a good opportunity to fight for the podium and we need to make sure that we continue improving the car over the course of the weekend."