The Red Bull driver, 24, who needed just one point to clinch the title, joins Juan Manuel Fangio, Ayrton Senna and Michael Schumacher as one of only nine drivers to successfully defend the world title.

He ran down the pit lane to celebrate with his mechanics after the race, which sealed the championship with four grands prix remaining following a dominant season with nine wins in 15 outings.
"There are so many things you want to say, but it's hard to remember all of them," Vettel said.
"I'm so thankful to everyone in the team, pushing hard to build those two cars. It's great to achieve the goal we set ourselves this year already.
"Today's race we weren't as quick on the soft tyres and we lost two positions, and it was difficult to get past Fernando."
At just 24 years and 98 days, Vettel outstrips fellow consecutive winners Alberto Ascari, Fangio, Jack Brabham, Alain Prost, Senna, Schumacher, Mika Hakkinen and Fernando Alonso as the youngest driver to achieve the feat.
Button's victory, which came after he passed Vettel in the second round of pit stops on lap 21, was his third of the season and the 12th of his career.
The McLaren driver finished 1.1 seconds ahead of Spain's Alonso of Ferrari, with Vettel's third place easily enough to secure the world title.
Australian Mark Webber was fourth for Red Bull, eight seconds adrift of Button, while Briton Lewis Hamilton of McLaren had another controversial race, clashing again with Felipe Massa of Ferrari en route to finishing fifth.
Schumacher was sixth for Mercedes, briefly leading the race after the final round of pit stops, while Massa was seventh.
Mexican Sergio Perez came through from 17th on the grid to take eighth for Sauber with a two-stop strategy, while German Nico Rosberg drove his Mercedes from second-last on the grid to finish 10th.
Vettel didn't lead last year's world championship until after the final race in Abu Dhabi, but this season he has never been headed in the standings.