Webber warns Texan autumn can slow Red Bull

A combative Mark Webber warned his Red Bull team on Thursday that the falling leaves and temperatures in autumnal Texas could cause them problems with their tyres during this weekend's United States Grand Prix. Hitting out at suggestions that in hot weather, the swooping brand-new Circuit of the Americas built 15 miles out of downtown Austin would favour Red Bull, he pointed out -- in robust Australian fashion -- that if their tyres were not working, the team would struggle. "I think our form card recently, apart from Abu Dhabi, has been very strong," he said. "Qualifying was strong in Abu Dhabi, at Suzuka we had the front row and cleaned up, and the other two races (Korea and India) were very strong (for Red Bull). "If we get back to that sort of form and you are in the hunt then victories are there, but temperature is very important. "Layout is not very important, temperatures are. If the black things on the corners are not working then you can put the layout up your arse - it is not going to work. "You need to have everything working together. I think the layout will not be too bad for us, but temperatures and understanding the tyres will be important." Webber's outspoken comments came after circuit designer German Hermann Tilke had suggested the spectacular circuit's demanding layout would present the drivers with their biggest challenge of the season -- and followed his Red Bull team-mate German Sebastian Vettel's apology for swearing during live television interviews following the Abu Dhabi Grand Prix. Following a recent warm spell, Austin has seen temperatures tumble to conditions that were far cooler on Thursday than those the travelling F1 circuit had become accustomed to in India and Abu Dhabi in the last month. Many paddock observers believe that Red Bull's car operates more efficiently in a warmer tyre operating window than does that of title rivals Ferrari. This suggests that cool weather could damage Red Bull's prospects more than Ferrari's and give two-time champion Spaniard Fernando Alonso a chance to cut into Vettel's 10-point lead. In addition to the falling temperature, Pirelli has opted to bring medium and hard tyres to the United States event - tyres that require a higher temperature to operate well compared to their softer tyres. "People talk about it being the best car," said Webber of his Red Bull. "It is fast, but there are still areas we need to work on, which we don't make for general consumption. "We have to work on those as a team and I think it has been a credit to the team how much we have developed the car through the year."