Valentino Rossi became only the second rider in history to regain the MotoGP World Championship after two successive defeats, when he won his sixth premier-class title with victory in Yamaha's home Japanese Grand Prix at Motegi on Sunday.

Rossi needed to finish third or better, even if nearest rival Casey Stoner won, to lift the championship three rounds early - but the 29-year-old Italian exceeded those requirements by charging from fifth on lap one to overtake leaders Dani Pedrosa and then Stoner by lap 14 of 24.

The Italian went on to claim his eighth world championship over all three classes by almost two seconds from the Ducati rider, while fourth for team-mate Jorge Lorenzo helped complete the triple crown of Rider, Manufacturer and Team titles for Yamaha.

"It's a great victory and a great achievement," smiled Rossi. "The race was a great battle and I had to ride at 100%, like I have through all through the season! Pedrosa and Stoner today were very strong and it was fun to fight with them like this, I am happy that it was a good race for the fans. It was a fantastic feeling to take the title with a win, like I did in 2001 and 2004."

Rossi's sixth world title leaves him behind only Agostini (eight premier-class titles) in the all-time standings and he marked the achievement with a special post-race celebration.

"The show after the race was one of my friends pretending to be a 'notary', signing and certificating the eighth championship 'deed," explained Rossi. "It was very exciting to be planning the championship t-shirt and celebration once again with my friends and fan club and the one we came up with is funny I think, it says 'I'm sorry for the delay!' "

Rossi was unbeaten in the premier-class from 2001 to 2005, winning the final 500cc crown and first two MotoGP titles for Honda, before a sensational switch to Yamaha saw his title run continue for a further two seasons.

But his dream run came to an end in 2006 when accidents, technical problems and bad luck - combined with a consistent attack from Nicky Hayden - saw the Honda rider claim the final 990cc crown. Things got worse in 2007, when Stoner and Ducati destroyed the opposition during the first year of 800cc competition, while Rossi and Yamaha slumped to third.

Rossi demanded improvements from Yamaha and a much improved 2008 spec YZR-M1, combined with Rossi's winter switch from Michelin to Bridgestone tyres, resulted in victory at round four of the 2008 season.