In the last nine weeks we've gone round the world twice
New Zealand head into their 14th and final Test of the year with the very real threat of fatigue setting in.
That is why it is no surprise that It will be a much revamped All Black side that will bid on Sunday to achieve what no team in the professional era has done and win all their Test matches in a calendar year by beating Ireland at Lansdowne Road.
Coach Steve Hansen has introduced seven changes to the starting line-up from the one that last Saturday avenged last year's defeat against England at Twickenham, but he is confident the fresher faces can round off the perfect year.
Their opponents - coached by New Zealander Joe Schmidt - face an awesome task.
Not only have they never beaten the All Blacks, they lost 0-60 the last time they met in Hamilton last year, but also the manner in which they lost 32-15 to Australia last Saturday has had some pundits commenting that they will be served up as a 'Sunday roast'.
No international team in the professional era has enjoyed a perfect calendar year - with South Africa's 1995 World Cup winning side, captained by Francois Pienaar, the last to achieve this with a perfect 10 from 10.
The New Zealand team led by Wayne Shelford, that won all seven of their Tests in 1989, was the last group of All Blacks to achieve the feat when Rugby Union was still an amateur sport.
However, New Zealand themselves came close to it again when they won 11 games and drew one under John Hart in 1997.
Hansen, who was assistant coach to Graham Henry when the All Blacks won the World Cup on home soil two years ago, is adamant that even with the radical changes, and without the experience of injured duo Dan Carter and Tony Woodcock, the side can create history.
"In the last nine weeks we've gone round the world twice, and this will be our seventh test in nine weeks," said the 54-year-old, whose side will be bidding to make it 14 wins from 14 matches.
"We've had a big, physical game against Argentina, another physical performance in Johannesburg, a lot of running and chasing in Dunedin, then France was physical and England was physical.
"It's just the accumulation of a lot of travel and game-time. We need fresh legs and we've got ability sitting there fresh, so why not use them?"
A lot of eyes will be fixed on Carter's replacement at flyhalf, 24-year-old Aaron Cruden, but assistant coach Ian Foster has few doubts about his ability to shine.
"Cruden can be very satisfied with his year as he has started a fair amount of tests and run the games really well, especially the first Test of the Rugby Championship against Australia [All Blacks won 47-29]," said Foster.
Foster, who was brought on board by Hansen after the World Cup triumph, said that neither complacency nor fatigue could be deployed as excuses if they slip up on Sunday and claimed making history was not on their minds.
"It's boring press but for us this game is just the next one, nothing more," he said.
"We're not seeing it as the last one. We're really pleased with the first two results [beating France and England] but we're not happy with the performances.
"We're ambitious and we are still chasing that great performance. So this match for us it is not relevant that it is either the last Test of the year or that the opposition is Ireland."
For Schmidt it is not a case of his suppressing his loyalties to his homeland, it is a case of delivering a good performance from a squad he says are a fine bunch of lads and in which he has placed his faith in flyhalf Johnny Sexton coming through alright despite a week spent battling a hamstring injury.
"This is a terrific group of guys who I have every faith in and if we avoid our defensive lapses from last week, we can match them," he said.
"It is a huge challenge but I always stick to the principle that in a two horse race anyone can win it."
However, 48-year-old Schmidt is under no illusions of the size of the task facing his side.
"They don't have vulnerable moments. Even when the other team is pressing them on their line, they turn the ball over and you are scrabbling back to prevent them scoring a try.
"They do not feel the pressure. They are a team for all seasons.