Williams driver Mark Webber says he expects to struggle in Sunday's British Grand Prix, despite an encouraging display last time out in Monaco.
He was third until a mechanical problem ended his race, but says his good form there will not count at Silverstone.
"Our Monaco pace has no relevance as Silverstone requires different characteristics from the car," he said.
"Silverstone is like Barcelona and based on our showing there, we've lots of improving to do."
"Monaco was not the right place to judge the new car but the car behaved well in the race"
Although he is Australian, Webber lives in England and says driving for a British team makes Silverstone seem like a home race.
"It's good to be able to go home each night and enjoy the familiar comfort of my own house, and also being able to share the weekend with friends and family which I don't often get to do," he said.
"Being a British-based team this race is always an important one for Williams too, both in terms of entertaining sponsors and enabling the factory-based members of staff to be a part of the weekend."
Like Webber, Toyota's Jarno Trulli also saw a promising race in Monaco scuppered by mechanical problems.
But he feels more confident about his chances as he has his second run-out in his new car.
"Monaco was not the right place to judge the new car but the car behaved well in the race," he said.
"It has also shown promise during testing so I'm confident the car is a step forward but we can't yet say how much.