If the All Blacks indeed trod the untrodden tonight against Ireland - the first side in the professional era to remain undefeated - their path to perfection has not been an easy one.
They could possibly have lost two tests this year - that brilliant, pulsating match against the Springboks at Ellis Park and last weekend's bruising encounter with England.
The Ellis Park test, the All Blacks' first win there since 1997, was really only brought under control with Beauden Barrett's try and finished off with a try (one of six he has scored so far this season) to the best player in the world this year: Kieran Read.
It was one of the best encounters between these two great rivals, a feast of commitment and attacking rugby - born, in part, by the need for the Boks to beat the All Blacks with a four-try bonus point to claim the Rugby Championship; opening the way for a fine attacking and counter-attacking test instead of the usual war of attrition.
That the Boks scored four tries against the All Blacks was a huge signal for the future for the South Africans; if they can cut down on the mistakes that fed an All Black team proficient in counter-attack, they will know they are building a side capable of attacking as well as the usual Springbok game plan of physical domination, positional and possession percentages, miserly defence and a precision goalkicker.