Highlights - Japanese Grand Prix (UK users only)
By Sarah Holt
BBC Sport in Suzuka
Red Bull's Sebastian Vettel wrapped up the 2011 world title as McLaren's Jenson Button saw his hopes end despite winning the Japanese Grand Prix.
If he won, Button needed Vettel not to score points to keep the championship alive but the German finished third behind Ferrari's Fernando Alonso.
At 24 years and 98 days, Vettel is the youngest double champion in history.
McLaren's Lewis Hamilton survived a puncture and another clash with Ferrari's Felipe Massa to finish fifth.
After an enthralling race on Suzuka's figure-of-eight circuit, Vettel joined the list of champions, which includes Ayrton Senna, Alain Prost and Damon Hill, who have been crowned in Japan and becomes only the ninth driver to take back-to-back titles.
Japanese Grand Prix - top three drivers
An emotional Vettel thanked his team afterwards, saying: "We took nothing for granted and we did it.
"I'm so thankful to everyone in the team, pushing hard to build those two cars. It's great to have achieved the goal we set ourselves this year already.
"This year we've always been this one step ahead. In a way the hardest thing is after winning last year to go out and do it again."
Button won an intense three-way fight for victory which ended with only two seconds separated the top three finishers and he was moved to take his first win in a country to which he feels close ties.
He has a Japanese girlfriend and has previously driven for Honda - and the race started after the country's national anthem was sung by a choir of schoolgirls from Fukushima, the town devastated in the 11 March tsunami which killed nearly 16,000 people.
"This circuit is very special to all of us so to get a victory here in front of this Japanese crowd means a lot," he said.
"This gives us a lot of motivation. To see three cars in a few seconds shows how competitive F1 is right now."
Vettel had wanted to wrap up the championship he has dominated from the first race in Australia with a 10th win of the season, but circumstances conspired against him.
The German found himself under investigation at the start of the race after he cut off Button's attempt to pass him off the line.
"He's got to get a penalty for that, hasn't he?" Button asked his team on the McLaren pit wall.
But the panel of stewards, which included 1980 world champion Alan Jones, said it was a fair move and took no further action.
"It was pretty brutal there's no doubt about it," BBC F1 co-commentator Martin Brundle said of the move. "Harsh but not worth a penalty."
Button was still angry about the incident after the race, and after congratulating Vettel,
he made his feelings clear
by asking the German: "Didn't you see me at the start?"
Vettel grinned and replied "you were behind", to which Button responded: "Come, on - halfway alongside. OK, that's how we're racing then."
Hamilton on 'shocking' Japan GP
After the first round of stops, Button had been slowly eating into Vettel's lead and took his revenge at the second round of pit stops when he made up a second in time in the pit lane and emerged ahead of the Red Bull on track.
But then it was Button's turn to see his advantage disappear when the safety car slowed down the pack so debris could be cleared off the track.
However, the 2009 champion burst clear at the restart and pumped in a series of fastest laps to build a two-second lead just after the halfway point of the race.
When Vettel made his third stop for the harder medium tyres he found himself emerging in ninth where he lost time among the midfield runners.
Button pitted two laps later and returned in third, resuming the lead with 12 laps to go - but the action didn't stop there for the Briton.
The tenacious Alonso had the McLaren in his sights and had closed to within 1.2secs of Button with two laps to go.
But Button responded with a new fastest lap of the race to take his third win of the season and a first in Japan, which he has described as his second home.
VETTEL - RECORD BREAKER
Youngest world champion: 23 years 135 days
Youngest back-to-back, double champion: 24 years 98 days
Youngest winner of a GP: 21 years 74 days
Youngest pole position: 21 years 73 days
Youngest on the podium: 21 years 74 days
Youngest to score a point: 19 years 349 days
A mistake in qualifying saw Hamilton start in third but he had taken advantage of Vettel's squeeze on Button off the line to sweep past his McLaren team-mate into second.
But a puncture to his right-rear tyre slowed down his progress and he was passed on track by both Button and Alonso before coming into the pits on lap eight.
Hamilton had arrived in Japan determined to put his clash with Felipe Massa's Ferrari in Singapore behind him - instead the pair tangled again, touching through the 190mph 130R corner.
Ferrari asked race director Charlie Whiting to investigate the incident but this time Hamilton escaped punishment.
The 2008 champion made a clean pass on Massa later in the race and finished fifth, which means he now heads to next week's race in South Korea looking for his first podium since the German Grand Prix.