Red Bull team chief Christian Horner said on Monday he expects a much tougher challenge next year after a dominant season in Formula One.
He said he believes his British-based outfit's back-to-back double triumphs in the drivers' and constructors' championships will have "upset" their main rivals -- and will stimulate a big fightback.
The Red Bull team won the constructors' title in Sunday's Korean Grand Prix thanks to a 10th victory this season by German Sebastian Vettel, who clinched his second drivers' title a week earlier in Japan, where he finished third.
"We are not foolish enough or arrogant enough to think that this kind of performance is normal. It is abnormal and it takes a super human effort to try and achieve," Horner said.
"For sure our competitors are going to be pushing hard over the winter. To do it once they can probably tolerate, but to do it twice probably upsets a little."
He said teams like Ferrari, McLaren and Mercedes-Benz should not be underestimated, and they would all be using the final three Grand Prix of the season to prepare for next year.
"The focus has to start moving towards next year. We have less than four months to design and build a completely new car," he said.
With that in mind, Red Bull's chief engineer Adrian Newey was already back in the UK, focusing on the RB8.
"The remaining races are the only track time other than a young driver test between now and when the new car is born," Horner said.
"So we will look to learn everything we can out of the track with the time we have available -- and that means pushing right up until the chequered flag in Brazil."