SILVERSTONE, England — As they get ready for the British Grand Prix this weekend, a sense of urgency seems to be creeping into the Ferrari, Lotus and Mercedes paddocks.

The talk Thursday was dominated by the abrupt announcement that Red Bull's Mark Webber is leaving Formula One after the season. But for the teams competing for the drivers' championship, the focus remains on Webber's teammate, Sebastian Vettel.

"I think he's doing a fantastic job. I think he's been nearly perfect in all the races with no negative races, always performing well in qualifying and doing very good races," said Ferrari's Fernando Alonso, who is second in the title race.

The three-time champion Vettel has shaken off some early season tire troubles and a controversy with Webber at the Malaysian Grand Prix. The German is back to his dominant best, with the surest sign being his performance at the Canadian Grand Prix this month in which he beat Alonso by 14 seconds.

The 25-year-old Vettel has a 36 point-lead over Alonso with 12 races remaining. Lotus driver Raikkonen is another eight points back in third and Mercedes' Lewis Hamilton is another 11 points behind in fourth.

Despite extending his lead, Vettel has tried to dampen down expectations that the championship is already his, insisting he was trailing at this time last season and needed a string of late-season victories to overtake Alonso. Should he win his fourth consecutive championship, Vettel would match the exploits of F1 greats Juan Manuel Fangio and Michael Schumacher.

His challengers understand they need to start beating Vettel.

"We need to keep fighting, we need to keep pushing and we need to recover from these bad races that we had now," Alonso said. "I think Red Bull is performing really well, it's improving compared to the first part of the championship, so we really need to raise our game if we want to catch Sebastian because he's doing a fantastic job."

Hamilton agreed.

"He's performing as the world champion that he is and they will be difficult to catch but I don't think it's impossible to close the gap," said Hamilton, who has had several podium finishes this season, including in Canada.

"From our side, we've already closed quite a huge deficit already so we're happy where we are. But of course we want to do better. Fernando's a lot closer. I think once they sort out their qualifying they'll be able to match the Red Bulls, if not beat them. So we need to do a lot more work."

Hamilton said his team is still having tire trouble and is struggling to translate the pace it gets in qualifying to the race.

Raikkonen spent much of the day fielding questions about a possible move to Red Bull. But he, too, was more worried with getting his season back on track after poor finishes in the past two races in Monaco and Canada.

"Obviously, it's not ideal but we can only try to improve the situation," he said. "If we can improve a lot and there are problem for the others it can change quickly the positions. There is still a lot of racing to go this year and we cannot lose much more points."

Meanwhile, Vettel's Red Bull teammate Webber announced Thursday morning that he's signed a multi-year contract and will compete in Porsche's new LMP1 sports prototype at the Le Mans 24 Hours race and in the world endurance championship next year.

The team only learned of Webber's decision Thursday and said it would take its time to find a replacement — with Red Bull principal Christian Horner simply saying he wanted a "fast driver."

"We want to field the best two cars we can next year," he said. "We are in a fortunate position where there are quite a few drivers who would like to drive a Red Bull car and we have two talented young drivers (Jean-Eric Vergne and Daniel Ricciardo) that we have been developing in Toro Rosso. We don't need to rush into a decision."

The 36-year-old is having a tough season, having failed to win a grand prix and lying fifth in the drivers' championship, 63 points behind Vettel. But the Australian has done well at Silverstone — having won two out of the past three races — and is confident he can add to his nine victories and 36 podium finishes before leaving F1.

"It's been a happy hunting ground around here, in Formula One and also, years before that in the junior categories," he said. "The Red Bull car in the last few years has also been pretty strong here, so we're looking forward to certainly challenging for another victory."