After starting from a low position of 14th, Button made several key overtaking maneuvers and steadily made his way through the field. His Brawn teammate and closest title contender Rubens Barrichello, a native of Sao Paulo, started on the pole but faded after making his first pit stop. Barrichello ran fourth in the closing laps before suffering a punctured left-front tire which led to an eighth-place finish for the hometown favorite.

"We are the champions my friends, we are the world champions," Button joyfully sang over his radio to the team after crossing the finish line.

Mark Webber from Red Bull took the lead after the first round of stops, and then easily held off Robert Kubica and Lewis Hamilton, last year's world champion, to win the Brazilian GP. Webber claimed his second career F1 victory. Kubica from BMW Sauber scored his first podium finish since one year ago in the Japanese Grand Prix, while Hamilton finished third for the second straight race.

Brawn and Red Bull have won a combined 13 of 16 grand prix so far this year.

Button began this season by winning six of the first seven races, but has not finished better than fifth since his victory in the June 7 Turkish Grand Prix. He will enter the November 1 season-finale in Abu Dhabi with an impassable 15- point lead over Vettel and 17 points ahead of Barrichello. A driver can score a maximum of 10 points only in each grand prix.

"Twenty one years ago, I jumped into a car and I loved winning," Button said. "I never expected to be world champion."

Button became the 31st different driver and the 10th Briton to win an F1 world championship. One year ago, his fellow countryman Hamilton from McLaren took the championship in dramatic fashion in Brazil. Hamilton's fifth-place finish allowed him to clinch the title by only one point over Ferrari rival Felipe Massa, who won the race. Massa, still recuperating from his injuries in a qualifying crash in Hungary, waved the checkered flag for the Brazilian GP.

Team principal Ross Brawn capped off a sensational maiden season by also winning the constructors' title in Brazil. During the offseason, Button and Barrichello's future in the sport were uncertain when their Honda Racing team folded. Brawn resurrected the team and surprisingly made it into a power house.

"It's just special," Brawn said. "The work the team did over the winter was sensational. All the people who couldn't be with us, because we had to re-size the team after the winter, my thanks go to them."

Red Bull's Sebastian Vettel entered the penultimate race of the season as the only other championship contender. Vettel qualified 16th in Saturday's rain- soaked session, but made key overtaking moves as well to give the young German a fourth-place finish.

The Brazilian GP began with a chaotic opening lap when Sebastian Vettel clipped Heikki Kovalainen, who then collided into Giancarlo Fisichella. Then Adrian Sutil, Jarno Trulli and Fernando Alonso were knocked out when they also crashed on the first lap. Trulli and Sutil engaged in a heated discussion after they collided.

"It was a very dangerous maneuver from Sutil," a frustrated Trulli said. "I think this guy is an idiot. He should look at what happened because it was very dangerous. That's why I am so angry."

Sutil claimed he was not the cause of the incident.

"It's very strange that [Trulli] came up to me and blamed me for the incident, because he just crashed into me."