(CNN) -- Sebastian Vettel became the youngest-ever back-to-back Formula One world champion with his third place finish in Sunday's Japan Grand Prix and the German now has an unassailable lead with four races of the season still remaining.





Vettel finished behind Jenson Button and Fernando Alonso at Suzuka, a result more than enough to retain his crown following a dominant season which has seen him claim nine victories and four second places from the 15 races so far.





With just four races still remaining, Vettel has an unassailable lead of 114 points over Button and cannot now be overtaken, although the battle for the minor placings is still likely to go down to the final race of the season in Brazil.





In fact, there were no changes in the top nine of either the drivers' or constructors' championship after Suzuka with the Formula One circuit now moving onto next weekend's Korean Grand Prix at Yeongam, the 16th race of the season





Drivers' standings after round 15 in Japan:





1. Sebastian Vettel (Ger) Red Bull 324 points





2. Jenson Button (GB) McLaren 210





3. Fernando Alonso (Spa) Ferrari 202





4. Mark Webber (Aus) Red Bull 194





5. Lewis Hamilton (GB) McLaren 178





6. Felipe Massa (Bra) Ferrari 90





7. Nico Rosberg (Ger) Mercedes 63





8. Michael Schumacher (Ger) Mercedes 60





9. Vitaly Petrov (Rus) Renault 36





Constructors' standings:





1. Red Bull 518 points





2. McLaren 388





3. Ferrari 292





4. Mercedes 123





5. Lotus Renault 72





6. Force India 48





7. Sauber 40





8. Toro Rosso 29





9. Williams 5
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