It could hardly be a tougher test of World Rugby’s much criticised disciplinary system because it is one that they almost cannot pass in the eyes of all.

Should Richie McCaw be banned from the World Cup final?

It is a match that has had destiny written all over it for the man and the sport from the start of this tournament.

Due to celebrate his 35th birthday long before the All Blacks have another Test match scheduled, he has hinted that he will retire at its end and it would be a fitting conclusion for a career such as his if he was to become the first man to lead a team to a defence of the World Cup and the first captain to lift the trophy twice.

However, in the modern parlance, a video went viral overnight following the All Blacks’ defeat of their greatest rivals, the Springboks, in Saturday’s semi-final and what it shows could not represent more of a conundrum for the citing officer and, more importantly, those who will pass judgement if he decides action should be taken.

It was the sort of thing that would once have happened repeatedly in matches without comment because at first sight it looks innocuous. McCaw heads round what turns out to be the wrong side of a ruck, realises he has to get change direction so veers to his right sharply then cuts back.

Only on a second or third look does it register that his elbow clips the head of Francois Louw, the grounded Springbok flanker, briefly forcing him backwards and one question is whether it was intentional or accidental.

Instinct says that for a player of McCaw’s ability and spacial awareness the collision could easily have been avoided and in truth it looks as if he simply could not resist a little cheap shot at his opponent.

That is what makes it the worst possible case, involving the worst possible player at the worst possible time for those who must rule on it.

There is already a school of thought that McCaw’s status in the sport means he plays in something of protected bubble, not quite untouchable by referees and authorities, but allowed to get away with things that others cannot.

If no action is taken on this incident this will be seen as the ultimate proof in the eyes of those who adhere to that view.

There is, however, another view that rugby’s disciplinarians contain among them some self-regarding people who are so determined to be seen to have ultimate authority that they could well seize upon this as a cause celebre because their pomposity means they dare not be seen to fail to act.

The questions then:

Are they brave enough to cite Richie McCaw and, perversely, are they brave enough not to cite Richie McCaw?

If so are they brave enough to find Richie McCaw guilty; and, again, are they prepared to risk further criticism by taking his career record into account and deciding that for what is a low end offence, with a recommended two week ban, he can be given no suspension?

It could not be more difficult to decide because even if it was deliberate it is hard to imagine that any referee would have red carded him had he seen it at the time yet it looks like a potentially dangerous act of foul play.

If it was any other player at any other time what would they do?

There are, inexplicably, McCaw-haters out there who would revel in him missing the World Cup final, but for most of us it would be a huge disappointment if he and we were denied his presence on the field and his bid to make further history in the final match of this greatest ever World Cup.

There should be no compromise. Either this is something that should be pursued or it is not. That it is such a close call could not make it more difficult for those charged with making it, but many of us are, like the man himself, simply hoping he is there to lead his team out at Twickenham on Saturday.

And Another Thing

Is McCaw the greatest player to have graced the sport of rugby. Steve Hansen is certainly among those who thinks so.

"We have got a captain who is probably the greatest player the game has ever seen and he is also a great skipper,” said the All Blacks head coach.

“In 2007 as a young captain he was criticised a lot and I know that hurt him."

That shock defeat at the hands of France in the quarter-final was one thing, but McCaw, who has been on the winning side in Test matches more often than all bar three men have played the game at that level, will be hurt much more if he is banned from next weekend’s World Cup final.