Everything indicates that Red Bull's 26-year-old German will become the sport's youngest quadruple champion with a flourish in what may well be Formula One's last appearance in India for the foreseeable future.
Since the race made its debut in 2011, Vettel has led every lap in India and arrives chasing a hat-trick of poles and wins at the Buddh International circuit in Greater Noida, south of the capital.
Alonso is the only man who can keep him waiting for the second race in a row and even victory will not be enough if Vettel takes at least fifth place. If the Spaniard retires, the matter will be settled on the spot.
Vettel has retired only once this season and finished at least fourth in all the other races. Even if the German fails to score, Alonso must still finish first or second to stay mathematically in contention.
The Red Bull driver is on a roll that could lead to more rewriting of the record books after he notched up five wins in a row in Japan this month to become the first driver since Michael Schumacher in 2004 to perform that feat.
Nobody, least of all his rivals, is ruling out the German winning the remaining races of the year to take his tally to nine in a row and equalling a record set by Italy's Alberto Ascari 60 years ago.
"If he doesn't have any reliability issues, I am willing to put money on it," commented Mercedes driver Lewis Hamilton after Suzuka.
Alonso meanwhile has not won since his home race in Spain in May and although he has finished second on five occasions this year, Vettel took the chequered flag ahead of him in four of them.
The last time the Ferrari driver finished in the top two with Vettel drawing a blank was in Valencia in June last year - 28 races ago.
Alonso can hope to be third time lucky, after finishing third in 2011 and second last year, but India is very much Vettel's track and Ferrari's main concern now is to beat Mercedes and hold on to second place in the constructors' championship.
Ferrari are only 10 points clear of Mercedes, with Lotus a further 23 adrift after outscoring both teams in the last two races, in a battle that is about prize money as much as paddock status.
Red Bull can also retain the constructors' title for the fourth year in a row on Sunday as an added bonus.
"So far everything has always gone perfectly for us in India. There is also a very nice trophy at the end of the race - so it would be great to hold one again this year," said Vettel this week.
It could be the last chance anyone has to get their hands on it. India is not on next year's calendar and although local organisers are talking about a return in 2015 few paddock insiders are optimistic.
The teams and organisers have been vexed by taxation issues while also wrestling with financial problems and slow ticket sales after drawing a big crowd to the inaugural event.
"I think it is very difficult once you leave a country to come back to it - especially where we have not really managed to establish the sport," said Sauber's Indian-born principal Monisha Kaltenborn.
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