Jenson Button sees Red Bull and Ferrari as the main challengers to Brawn GP at the Malaysian Grand Prix this weekend.

The Formula One newcomers will be looking to emulate their magnificent debut in Melbourne last weekend.

The Englishman was followed home by Rubens Barrichello in a one-two finish at Albert Park, leading many to believe that Brawn will be a dominant force this season.

But Button believes it is too early to write off the rest of the field and expects a competitive race at Sepang this Sunday.

"It's difficult to say after one race, really, that we're unbeatable," said the 29-year-old.

"Red Bull were obviously quick, quicker than what we expected in Melbourne. I didn't think that they would be the team that would be up there at the front.

"I also think that Ferrari will catch up, they always do.

"Those two teams are the teams for me that will be competitive going forward and also BMW.

"It's a very strange mix with teams this year. It seems to be very close. We seem to have a slight advantage and then everyone else is very close and in the mix.

"It makes it exciting and I think different people will stand out at this race."

Despite the team's successful outing in Australia, Button feels that the circumstances in the race, which featured two safety car periods, made it difficult to gauge the true performance of the Brawn.

He hopes to get a clearer picture this weekend.

"We don't really know how much advantage we had in Melbourne.

"It's difficult to say with the safety cars and what have you but it wasn't a perfect weekend in Melbourne.

"If we get a perfect weekend here, obviously we'll be looking strong but this is a very different circuit and I think some of the other teams could be strong here.

"I think that the cars with KERS, as far as we know, will have a bigger advantage than they had in Melbourne, so they are obviously ones to watch out for - especially Ferrari, so we will wait and see.

"We hope we have an advantage but we won't know until qualifying on Saturday."

Having struggled at the back of the field for the last two years, Button is understandably delighted with his current position at the top of the driver's standings.

"It is obviously a good feeling," he admitted.

"The strange thing is that after the winter we had and the last couple of years, you do the first race and you win it and it is obviously exciting and quite emotional, but you get over that pretty quick and are on to the next race.

"You get used to being at the front very quickly. I suppose it's what we have all done in the categories leading up to Formula One."