As late as the Thursday morning of the 2007 United States Grand Prix, Vettel wasn't going to be racing. Reserve driver for BMW-Sauber, he was though on alert - Robert Kubica's massive crash in Canada just four days earlier meant the Pole had to be medically cleared before he could compete.
Having escaped with only bruises and a sprained ankle, Kubica insisted he was 100 percent ready. The doctors, however, saw it differently. Vettel was in.
"For him [Vettel] it is a great opportunity," Kubica told the media. "I am sure he will use it well."
And so he did.
While not exactly a newcomer to F1 machinery - Vettel had driven for BMW-Sauber in seven FP1 sessions prior to Indianapolis - he was new to the circuit, with two laps by foot his only first-hand experience. At the end of the first session he was fourth fastest; by the end of Saturday he had made it into Q3, winding up seventh, just half a second and two spots off new team mate Nick Heidfeld.
"Towards the end I could have been a bit better, but making it into qualifying three was already a big step," Vettel reflected afterwards. "I shall sleep better tonight because last night I had the unknown ahead about what will happen."
As it was, Vettel's dream debut very nearly fell apart at the first hurdle. A slow getaway left him vulnerable heading into the first turn, and convinced the rookie to go very late on the brakes to keep track position. It was a misjudgement.
Barrelling to the outside, the German was suddenly carrying too much speed just as those ahead squabbled over position. Wheels locked, smoke pouring, Vettel was forced to take emergency evasive action and head for the run-off. By the smallest of margins - mere inches - he got away with it.
"I decided to brake a bit later to keep the contact to the field in front," he confessed to afterwards, "but it was a bit too late and I could not finish all of my braking as there was [Heikki] Kovalainen braking and fighting with another car and being quite slow in that moment.
"I decided to go straight and cut the grass. Otherwise I would have hit him, and then for sure his race is over - and mine..."
The mistake sent him tumbling to 11th, and also left him stuck in traffic, but Vettel was not to be denied his moment. A gradual fight back carried him to ninth, with the German even harrying future team mate Mark Webber, before fortune turned decisively in his favour on lap 68 when Williams' Nico Rosberg retired. Five laps later and the chequered flag fell: Vettel had claimed eighth, and broken Jenson Button's seven-year record to become the youngest points scorer in history.
It was not the only slice of history written that weekend, of course. Fernando Alonso and Lewis Hamilton's intra-team rivalry at McLaren escalated, while Scott Speed made what remains the last start by an American driver on home soil - until this weekend at least.
But on a sweltering Sunday in Indiana, a precocious teenager showed the first glimpse of his staggering talent.
The rest, as they say, is history...