Jenson Button and his Brawn GP team were crowned Formula One champions with a race to spare in an action-packed Brazilian Grand Prix won by Red Bull's Australian Mark Webber in Sao Paulo on Sunday.

Button finished fifth to become Britain's 10th world champion, with closest rival and teammate Rubens Barrichello suffering the heartbreak of a late puncture and finishing eighth after starting his home race on pole position.

While Barrichello's own title hopes were fading anyway before that, nothing could stop Brawn from becoming the first team to take the constructors' crown in its first full season.

Button, who belted out an off-tune "We Are The Champions, My Friends," over the team radio on his slowing down lap, was ecstatic after a rain-hit qualifying session had left him starting 14th.

"I am the world champion, baby, and I'm not going to stop saying it," he yelled. "This race for me was the best race I've driven in my life, probably," added the 29-year-old. "I know it's because of the emotion involved with it but also because I knew I had to make it happen."

Second win

Webber celebrated the second win of his career, with Brazil's injured Ferrari driver Felipe Massa waving the chequered flag.

"I think he (Button) can sleep better now because he's been absolutely bricking it after the last few races," Webber said with a smile, his victory completely eclipsed by the Brawn celebrations. "He can enjoy (the last race in) Abu Dhabi."

Red Bull's Sebastian Vettel, the 22-year-old German who had needed to finish in the top two to have a chance of staying in contention for the title, took fourth place.

Button, winner of six of the first seven races, now has 89 points to Vettel's 74 and Barrichello's 72.

Poland's Robert Kubica was second for BMW-Sauber with McLaren's outgoing world champion Lewis Hamilton taking third place from 17th on the grid.

The safety car was deployed for four laps after chaos on the opening one when Force India's Adrian Sutil, Toyota's Jarno Trulli and Renault's Fernando Alonso crashed out. Trulli and Sutil almost came to blows on the runoff after they stepped out of their shattered cars. Race stewards fined Trulli US$10,000 for his actions.

McLaren was dealt a US$50,000 fine for the unsafe release of Heikki Kovalainen from the pits. The car pulled out with the hose still attached, spraying fuel over Kimi Raikkonen's Ferrari.