Don't expect instant results of Pedro, says Frank

The British team dumped driver Luciano Burti last week because they were unimpressed with the Brazilian's pace on the track this season. He was replaced by promoted tester de la Rosa, who partners Ulsterman Eddie Irvine this weekend in Spain for his home race.

The Spaniard qualified a lowly 20th, a full second behind Irvine's 13th on the grid, while Luciano Burti starts 14th, a place ahead of his new team mate Jean Alesi.

"The cars are very complex and the teams too," said the Williams team boss. "It takes a long time to find out who is who, what is what, and which buttons to press.

"It does not come to a new driver in a few days or even a few weeks. It will take half a season at the very least."

Williams has also played down his team's chances of a second Grand Prix win on the bounce after Ralf Schumacher's San Marino triumph two weeks ago. He claims the team's BMW-powered car will not be up to speed at the Circuit de Catalunya.

Williams added: "A lot has changed in a fortnight. Yes, we were looking good 14 days ago, but after Friday's events there is not great confidence in which I could say 'no problems mate'. We are a long way away. Don't be too sure for us."