If the All Blacks' collapse against England revealed anything, it was that the line between success and failure in international rugby is fine - and the importance of mental preparation.
It was one of the reasons All Blacks coach Steve Hansen didn't appreciate the talk about his side, who up until last weekend were unbeaten for 20 tests, being the best ever. That can lead to complacency and short-cuts in preparation, both of which are anathema to any coach. But the question remains: were the All Blacks, regarded as the fittest side in international rugby, mentally all there at Twickenham?
The 14th and final test of a demanding year against an opponent with plenty to prove was always going to be difficult but the uncertain start and failure to kick on once fighting back to trail 15-14, and associated defensive disasters, was out of character.
Last year's World Cup meant the All Blacks didn't tour the north but, in 2010, they played 14 tests and comfortably accounted for England, Ireland, Scotland and Wales at the finish. The difference this year was the shoehorning of three tests into the Super Rugby season, which meant it didn't finish until August 4. The toll it and other factors took on the All Blacks was plain to see last weekend.
"No excuses," Hansen said, when asked if the virus suffered by many of his players during the week was to blame. But something clearly wasn't right - whether physical, or mental. Centre Conrad Smith gave an insight into the team's thinking when talking about looking forward to a break.