Sebastian Vettel's place in the annals of F1 history remains uncertain after Ferrari admitted that it was studying footage of an overtaking move that could still - four days after the event - see the German stripped of his third successive world crown.

The Scuderia, which apparently does not need to lodge an official protest to see the destiny of the title change dramatically, has confirmed that it is trying to establish whether there is sufficient proof that Vettel passed Jean-Eric Vergne 'under yellow flags' during last Sunday's rain-affected Brazilian Grand Prix. Vettel's overtaking manoeuvres have been the subject of internet conjecture since television pictures apparently caught Vettel 'in the act' of passing Kamui Kobayashi in a yellow flag zone approaching the main straight, but that incident was dismissed by race stewards at Interlagos as involving a red/yellow signal denoting a slippery surface rather than a no overtaking zone.

Now, however, on-board footage from the German's RB8 apparently shows him passing Vergne in a similar situation. Vettel is alleged to have passed two yellow lights and Vergne's Toro Rosso before reaching the green light signifying the 'all-clear' to resume racing.

Should Ferrari, and the FIA decide that there is a case to answer, Vettel could be hit with a post-race time penalty, which would be enough to drop the Red Bull driver from sixth to eighth place, costing him enough points to concede the title to Fernando Alonso. The Spaniard trailed by three points on the final reckoning as the F1 family partied in Sao Paulo last weekend, but Vettel stands to lose four points should his misdemeanour be proven.

Despite the result having been finalised on Sunday evening, the rulebook allows a grace period for incidents to be investigated - and acted upon - giving the authorities until Friday (30 November) to determine the destiny of the title. The FIA, which does not need to be presented with an official protest to act retrospectively, has so far refused to confirm that it is investigating the incident, but its own regulations reveal that it would be obliged to investigate.

"If, in events forming part of an FIA championship, a new element is discovered, whether or not the stewards of the meeting have already given a ruling, these stewards of the meeting or, failing this, those designated by the FIA must meet... to hear any relevant explanations and to judge in the light of the facts and elements brought before them," Article 179b of the F1 sporting code confirms, "The period during which an appeal in review may be brought expires on 30 November of the year during which the decision that is liable to review has been handed down, if that decision is likely to have an effect on the result of a championship."
Video footage, which has appeared on YouTube since the race, appears to show Vettel passing Vergne on lap four of the 71-lap race, while the local caution covered the clear-up process resulting from the German's contact and spin on the opening tour. The film was not seen by television viewers - and therefore not subjected to the same sort of scrutiny as the Kobayashi incident - as the FOM-controlled world feed was concentrating on repeats of the start, and Vettel's clash with Bruno Senna, but should have been available to race officials.

Initial viewing of the footage suggests that Vettel may have been confused by a green flag that appears to be shown at the left of the circuit on the previous lap, when the German's recovery drive saw him slice past Charles Pic. Ferrari and the FIA now need to prove that the flag was not being shown immediately before Vettel's move on Vergne.

The Spanish media has, naturally, been whipping up a storm over the incident - believing Alonso to have been a deserving world champion following two first lap exits not of his making that stripped away a lead that once stood at 40+ points. According to reports in his homeland, Alonso is supposed to be pushing Ferrari to lodge a protest before it is too late to make him a three-time champion, following previous successes with Renault in 2005-06.