Sebastian Vettel is forced to quit the British Grand Prix Sebastian Vettel bounced back to his best on Friday afternoon when he led the way for Red Bull in the second free practice for this weekend\'s German Grand Prix at the Nurburgring.
On a warm and dry afternoon in the Eifel, the defending triple world champion and current series leader clocked a best lap in 1min 30.416sec.
That put him two-tenths of a second clear of nearest rival and fellow-German Nico Rosberg of Mercedes, as the pair made the most of home support to emerge as likely leading contenders for pole position on Saturday.
Australian Mark Webber was third quickest in the second Red Bull, close behind Rosberg but ahead of Frenchman Romain Grosjean and his Lotus team-mate Finn Kimi Raikkonen, the 2007 champion.
After the dramatic tyre problems seen a week earlier at Silverstone, where four drivers suffered high-speed blowouts during the British Grand Prix, there were no problems with the new Kevlar-strapped tyres supplied by Pirelli.
Two-time champion Spaniard Fernando Alonso was sixth quickest in the afternoon, ahead of Ferrari team-mate Brazilian Felipe Massa, after failing to clock a lap in the morning.
Briton Lewis Hamilton, the 2008 champion, was eighth fastest in the afternoon, after dominating morning practice, ahead of former team-mate and compatriot 2009 champion Jenson Button of McLaren.
Another Briton Paul Di Resta was 10th fastest ahead of his Force India team-mate German Adrian Sutil.
Friday morning\'s session was the first to be run using the new Kevlar-belted tyres.
In a move to endorse Pirelli\'s switch of tyres on safety grounds, the sport\'s ruling body on Friday morning announced it was imposing a ban on tyre swapping and strict limits on tyre pressures and cambers.
In a note that was sent to all the teams, the International Motoring Federation (FIA) race director Charlie Whiting said: \"For safety reasons, we have been asked by Pirelli to ensure that the tyres on all cars are run under the conditions listed below.
\"It will be the responsibility of each team to satisfy the FIA technical delegate that the cars comply with the following requirements at all times.\"
This move from the FIA came after Pirelli wrote to motor racing\'s governing body on Thursday requesting that teams are limited in how they exploit the rubber, because that was viewed as a contributing factor in the Silverstone failures.
Whiting added in his note: \"Front and rear tyres must be used on the side of the car for which they were originally designated (meaning no swapping from side-to-side.)\"
Amid this flurry of guidelines, and following a threat late on Friday from the drivers that they would pull out this weekend if there was any repeat of the tyre problems, Pirelli motorsport chief Paul Hembery conceded that the failures at Silverstone were their responsiblity.
\"We allowed the teams to invert the tyres when we shouldn\'t have done,\" he said. \"With the cars going much quicker this year that creates different loads.
\"With the inverted tyres you create a weakness point, and that was the issue. There were secondary issues, which have been mentioned, but I don\'t want to take away from the fact it was our responsibility.
\"Going forward, though, there are things we need to be much more rigid on, and that\'s where we are at.\"
The chairman of the Grand Prix Drivers\' Association, Pedro de la Rosa, praised Pirelli\'s moves to address the issue, saying safety was paramount.
But he warned that drivers would meet to discuss their next move if there were problems with tyres during qualifying and the race itself.