Button still wary of big guns

Ferrari, McLaren and BMW Sauber have so far mustered a meagre 25 points between them after five grands prix, still a whopping 43 points shy of the total amassed by the flying Brawns.

And pacesetter Button said: "They've had tough years before, maybe not quite as tough, but they will definitely bounce back. They're very strong teams, and we'll see them being competitive throughout the year."

Sunday's Spanish Grand Prix should have been the time when Ferrari and BMW Sauber in particular underlined their strength in depth and their resources.

The Prancing Horse marque kicked briefly into life, but errors and reliability again undermined their weekend, leaving under-pressure team principal Stefano Domenicali facing more questions rather than delivering answers.

Instead, it was Ross Brawn's team who proved their early-season form is here to stay, and they are title challengers to be feared and respected.

Button, who made it four wins out of five with his latest victory at the Circuit de Catalunya, is convinced the top trio will ride the storm. Assessing their form, Button said: "It's quite strange.

"In Bahrain, McLaren were surprisingly quick, the same with Ferrari in Barcelona in qualifying. They've had good races, but they just haven't had the consistency. When you've started so far back compared to the competition, you're throwing things at the car.

"I'm sure they're putting lots of new parts on the car to improve it. Some might not work, some probably do work.

"It's a much easier position for us, obviously, at the front. We can really test the parts and make sure they are an improvement before we put them on. Whereas Ferrari and McLaren need to put as much performance on the car as possible. But they're both great teams and they've both achieved so much in the past, as we all know."