The last man to win four consecutive Formula 1 championships, Michael Schumacher, praises his "friend" Sebastian Vettel for achieving the same feat.

BBC Sport looks back at some of the key moments of Vettel's season as he stormed to his sixth consecutive victory to take the 2013 world title at the Indian Grand Prix

The 26-year-old German is only the fourth man in history to win four titles, joining motor racing legends Juan Manuel Fangio, Alain Prost and Schumacher.

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