Mat Coch & Chris Balfe write:

The pressure is on Renault after another alternator failure eliminated Red Bull's Mark Webber from the United States Grand Prix, prompting nervous times for the newly crowned Constructors' Champions.

Having secured its third (or more) consecutive constructors' title in Austin, becoming just the fourth team in the sports history to achieve the feat - Ferrari 1975 - 1977, Williams 1980 - 1982, McLaren 1988 - 1991, Williams 1992 - 1994 and Ferrari 1999 - 2004, Red Bull is now targeting the Drivers' Championship. The squads' double-world champion Sebastian Vettel currently heads the standings by thirteen points, though Webber's retirement has raised questions about the team's reliability and will likely result in a few sleepless nights for Christian Horner's outfit.

"Reliability is a concern," confessed Red Bull designer Adrian Newey to Sky Sports F1. "It's unfortunately our third alternator failure this year which is a ticking time bomb.

"You never know when that one is going to strike," he admitted. "Renault haven't managed to find a proper solution to that one so that's a continual worry in the back of our minds as is the rest of the reliability.

"The cars are very complicated and keeping them going around is anything but guaranteed."

Vettel was forced out of the lead in Valencia as a result of an alternator failure. He joined Romain Grosjean on the list of retirements that weekend when the Frenchman's Renault engine suffered the same fate. In September, Remi Taffin, Renault Sport F1's head of track operations, apologised to Red Bull after Vettel suffered two failures across the Italian Grand Prix weekend.

"We introduced a new spec of alternator following the problems in Valencia and believed this would overcome the issues," explained Taffin at the time. "This is a priority between ourselves and our suppliers and we have to ensure we are fully on top of the problem before Singapore."

Ironically, Renault had developed a newer spec alternator, which it made available to teams for the United States Grand Prix. While others chose to run the new part Red Bull opted for a conservative approach, using the same alternator which it had used without problem since the Italian Grand Prix.

In a further touch of irony, at the FIA press conference, Webber was (wrongly) informed by a journalist that he would be using the new alternator. "Good journalism. It's good that you know more than me," mocked the Australian. "I trust the guys, they do whatever they can to make sure that we have the best possibility to have the smoothest Sunday afternoon, irrespective of what parts are on the car, in what area of the car. So I have one hundred per cent trust in them that they're going to do what they can to get us home and they've obviously selected those alternators for a reason and put their best foot forward."

Should Vettel be forced out of this weekend's Brazilian Grand Prix for any reason Fernando Alonso must finish third or better to secure his third title. Vettel needs only to finish fourth or better to be guaranteed the title regardless of where Alonso finishes.

Renault has just four days in which to solve a problem which has plagued it since the European Grand Prix in June.

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