Button at a loss to explain lack of pace

The championship leader was expecting to fight in front after a strong Friday, but instead found himself out of the top ten shootout, down in 12th position.

Button qualified behind his team-mate Rubens Barrichello, who was fifth fastest but dropped to 10th due to a penalty for changing his gearbox.

The British driver admitted he was surprised not to be quicker.

"It's been a tough and a strange qualifying for us," Button told reporters. "We've had very good pace all weekend and it is strange to not be quick. I don't even think Rubens was happy with being P5. I think they expected more.

"So, with the fuel loads that he has on, I don't know if it is less than the people who are in front of him. We have to wait and see on that one, but he saved a couple of laps by making that mistakes.

"But this is a circuit where we thought we would be very quick and so far in qualifying we haven't shown that. It is weird how things go and how races seem. Some races we are very quick and some circuits we struggle more, especially when we get to qualifying. It is the same with the Red Bulls.

"Mark [Webber] has not scored in the last three races and while Vettel has, it is a lot less than he would have hoped. And they are now back strong. It is very up and down and a unique season for sure."

Button said he was at a loss to explain his sudden lack of pace, and was disappointed to have qualified so far behind the Red Bull drivers.

Sebastian Vettel was second, with Mark Webber in fourth.

"Suddenly we were struggling a bit more in Q2, so it is difficult to know the reasons for that. Being back in 12th is disappointing," he said.

"Rubens is just in front of me because of his gearbox change and probably on quite a bit less fuel, so there is still a lot we can do tomorrow.

"It is frustrating being so far back, and the Red Bulls are at the front. They still have a chance of challenging us in the championship, so we've made it very difficult for ourselves. That is all I have to say."

Despite Vettel being 26 points behind him in the standings, Button reckons the Red Bull drivers are still in contention for the championship.

"A threat? Yes I think so," he said. "It is so up and down that it is really hard to predict who is going to be quick where. I said it was disastrous in an early interview when I got out of the car but that was emotion really. It is not disastrous.

"It is not perfect being back in 12th position, which makes it very difficult to score points here, and the Red Bulls from where they are can have a good race. It will be very difficult for them to beat Lewis, and I think Rosberg will be very quick also. It will not be a walk in the park for them for sure. It is good to see other cars are competitive."