Button: Brawn not Sepang favourite

Alhough his Brawn GP outfit was dominant in the season-opening Australian Grand Prix, and rivals have said he and Rubens Barrichello are untouchable, Button reckons the competitive picture has already changed at the second race of the season.

With Kimi Raikkonen and Felipe Massa leading the way in Friday practice, Button believes his team is no longer favourite - especially as it does not have a KERS system.

"I think we have got a lot more competition this weekend," said Button, who won from pole position in Melbourne.

"We are not there with the balance yet. I have a lot of areas to work on, where I am not happy. That is a good thing because I don't think our pace is as good as we would have hoped.

"I think if you look at the cars and their long runs, you can see the Ferrari is very quick and you can see the Red Bull is quick. Especially, the Ferraris are a lot quicker than I expected, so they are very competitive. I am not sure if we can do the same times as them, so we have to wait and see."

He added: "At the moment we are not in a position that I am happy with, with the car. I think Rubens is the same. There are areas where we really need to improve to be at the front, and you might think it sounds crazy or that I am trying to talk us down - but I think Ferrari is the team to beat if you look at the times at the moment. And that is not just over one lap; it is over the long runs.

"So if they are running a reasonably normal fuel load, which I think they probably are, they are very quick. They are going to be the cars that we have to beat."

Button is especially wary of Ferrari because it is one of the few teams running KERS - which will provide an advantage on Sepang's long straights and at the start.

"You cannot compete with KERS cars on the straights here," said Button. "I was behind [Fernando] Alonso here in practice and he was annihilating me on the straights. So they are gaining a lot on the straights, probably more than they have let on in previous tests and what have you. But that is an area where they are going to be strong.

"So even if I do qualify in front of them, it is going to be difficult to keep them behind. It is tough when you are racing against KERS cars, and when KERS cars are your main competitors, it is going to be very difficult."