Ross Brawn won't be found sleeplessly pacing up and down the corridors of his Sao Paulo hotel room ahead of arguably the biggest weekend of his illustrious career.

Brawn looks certain to oversee his eponymous team win him the eighth constructors' title of his career at the Brazilian Grand Prix - they need just half a point to wrap up that particular title - and it is conceivable that Jenson Button could also win the drivers' crown at Interlagos.

Brawn's bid could still all fall apart at the seams but the unflappable 54-year-old, who boasts three decades in Formula One, remains as calm and composed as he has been all season.

"I think about things I can influence and call it a day when the last of those are done," said the man known as 'Big Bear' by his team.

"It's a case of dealing with the things I can influence. Sure, I can have sleepless nights during the season but not from worry, just jetlag."

It is this sort of calm that has kept Button's championship bid on track rather than derail as it could so easily have done and, should he replace Lewis Hamilton as world champion, then he is all too aware where the biggest credit belongs.

"A lot's changed within the team from last year to this year and Ross's input has been the key," explained Button. "He's won so many championships and he's been in every situation imaginable, which has been vital at every turn."

As the name would suggest, Brawn is at the heart of everything the Brawn GP does. Having joined Honda ahead of the 2008 season, he immediately set about working on the car for the 2009 championship.

And when Honda pulled the plug on their F1 operation, one of the quiet men of the sport, far happier working on the technical intricacies of a car than holding court with the media, led a management buy-out.

Brawn readily admits it was never his intention to front his own team - he calls it a "happy accident" - although he is unlikely to complain if and when the team wrap up both world titles nor will he take credit for the achievement such is his modesty.

"This is all down to a very good team and I've worked with some very good teams in the past," added Brawn.

"There's a good atmosphere in the team and it reflects the fact that people aren't afraid to give me nicknames, but there's a nice respect as well."

Brawn is seen by most, including Michael Schumacher, as the reason for the German's long-term success in F1, first at Benetton and latterly for a decade at Ferrari, with Brawn his technical director on both occasions.

While Brawn looks back at those successes, a constructors' title under his own name would surely be more special than the one achieved at Benetton and the six he won while at Ferrari, although he has yet to admit it.

He owes his big break in F1 to another team boss on the grid, Frank Williams, who employed him as a 23-year-old machinist in the late 1970s.

However, Williams admitted: "I can't remember thinking he was destined for greatness but he was very clever, that much was clear and he took in everything he was told or saw. That was his great strength - there was never a case of in one ear and out the other with Ross. I hope maybe I taught him something along the way."

Despite his cool exterior, there have been moments when Brawn has been tested this season: notably Button's dip in form and at the German Grand Prix when Rubens Barrichello accused the team of favouritism towards his rival.

Brawn has ultimately been rewarded for starting on the 2009 car arguably earlier than any other team and for his bold interpretations of the rules and in particular the initially controversial double diffuser.

It is that technical acumen, allied to his management skills and tactics, that have turned the least likely success story of 2009 into potentially F1's greatest fairytale. "For me, just getting on the grid was an achievement and everything else has been a plus," he said.