Jenson Button believes that Red Bull Racing will continue to be the long-term threat to Brawn GP's championship chances, as expected frontrunners Ferrari, McLaren and BMW Sauber struggle to mount a consistent challenge.
The Briton was speaking in the wake of his fourth win in five races, in Barcelona, where Mark Webber and Sebastian Vettel chased home the two BGP001s to underline RBR's status as second best team to Brawn over the opening quarter of the season. The pair are also the closest challengers to Button and Brawn team-mate Rubens Barrichello in the championship, despite neither having had a perfect start to the year.
"Mark and Sebastian were both held up behind [Felipe] Massa and, if they had had free runs, we don't know what would have happened," Button said after the second Brawn 1-2 of the season, "I'm very surprised that Mark was able to sit on the back of Rubens, but I think that, when Red Bull have a clear shot at it and they do everything right, they are going to be competitive.
"Mark and Sebastian are doing a great job. Sebastian's been ahead of us twice now in the last two races so, if he gets a free shot, like Mark, he'll be close when they get it together. They've got good pace, and we can't forget that. They are going to be on us in Monaco, for sure."
Apologising for the fact that his strong start to the season may have made things a little more boring than expected in Formula One's brave new world, Button insisted that he needed to accrue as many points as possible while he had the chance, for RBR and the rest of the field would not be stinting on development. And, even though he rated Red Bull as Brawn's biggest threat, the Briton was not ready to rule out a challenge from the erstwhile 'big three' as the year wore on.
"I think that, at this point of the season, you need to be aggressive and you need to fight for every single point," Button insisted, "There's no point hanging back and expecting it to happen. We need to be very aggressive and we need to get everything out of this car at every race we go to. Five races in and [we've got] a reasonably good lead now. It's a good feeling, but I'm not getting comfortable as Rubens is very quick and also the Red Bulls.
"Also, [Ferrari and McLaren] are very strong teams. We'll see them being competitive throughout the year. McLaren, at the last race, were surprisingly quick, the same with Ferrari here in qualifying, so they've had good races, but they just haven't had the consistency. I think that, when you've started so far back compared to the competition, you're throwing things at the car and I'm sure they're putting lots of new parts on the car to improve it. Some might not work, some probably do work, but it's a much easier position for us, obviously, at the front.
"We can really test the parts and make sure they really 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. They've had tough years before, maybe not quite as tough, but they will definitely bounce back."
Button's team principal, Ross Brawn, shares the view that Red Bull will continue to pose the biggest threat for victory.
"They've a very strong team, a good group of people and good drivers, so it looks that they're the main challenge to us," he said, "Other teams will come and go during the season but, in terms of a long-term challenge, then Red Bull look very strong.
"If Vettel had had a clear track [in Spain], he would have given us a very hard time - he had a lot in hand, but just couldn't use it, which is the second race he has not been able to show what he can do."