LONDON: It was one thing for the Brawn team to turn up at the last minute for the start of the season in Australia on 29 March and quite another to finish a punishing five-week Asian tour on top of the championship. Ross Brawn will be glad of the pause before the season resumes in Spain, however, Brawn GP's team principal admitting they had "nothing in the cupboard" to sustain Jenson Button's remarkable run beyond his third win from four races in Bahrain on Sunday.

The Brawn-Mercedes may have been untouchable in Melbourne but the ferocious pace of evolution in formula one means the opposition will be hot on their heels and, in the case of Red Bull, poised to overtake thanks to a fine win for Sebastian Vettel in China. "We have had no upgrades for the first four races because there was nothing there," said Brawn. "Getting to the first race was as much as we could manage and there was nothing in the cupboard. Australia was perhaps one we could only throw away, whereas Bahrain was one we had to win.

"My worry was the engine because in qualifying it was running too hot. Because it all got thrown together at the last minute, we had underestimated the water cooling. The conditions were so hot in Bahrain that it was compromising the car. During practice, the drivers could only do one fast lap and then they had to cool the car down. When Jenson qualified fourth and Rubens sixth, it wasn't looking good, to be honest."

All 10 teams will be flat out between now and the Spanish grand prix on 10 May to improve their cars but if Brawn can provide Button with the right upgrades at the Circuit de Catalunya the odds on the 29-year-old becoming champion will dramatically shorten. "I've got no doubts about Jenson's ability to win," said Brawn. "The way he is driving, that part is taken care of. It's up to us to produce the performance in the car, do the strategies, and make sure the car is reliable."

Button also admitted that he had been worried about the car's ability to withstand the heat in Bahrain. The second row was not the ideal starting place for a car that needed to be running in clear air as the ambient temperature reached 38C."After Shanghai, where I finished third, I wanted to get back on the top step of the podium again," said Button. "We thought we would have a good car in ­Bahrain, but it didn't seem to be working out that way. We'd lost some of our pace. We were worried about our temperatures to the point where I thought: 'If I'm in ­traffic in the race, we're screwed. We won't be able to run it at the pace we want, we're going to have to back off.'

"Luckily, more people didn't get past me at the start when I had clutch slip. My main worry was Vettel but I managed to get past him at the first corner. I was chuffed to bits with that move. I had to conserve the engine in the last stint because it was getting very, very hot – and that was with no traffic in front.

"This win was very sweet because, after qualifying, we didn't expect it. Everybody seems to have caught up and Red Bull have actually overtaken us. The parts on the car are getting very old now (in racing terms). We need to get back to base and freshen everything up and hopefully make another step forward."

McLaren, following Lewis Hamilton's encouraging fourth place on Sunday, can only hope they remain a part of it following the outcome of tomorrow's investigation into allegations over the team's dishonest conduct in Australia. Disqualification is the ultimate sanction available to the motor sport world council.