You can't really look too far past Scotland's defensive effort if you're looking for reasons why they beat England on Saturday.
The defence was incredibly well organised and Frank Hadden got his tactical substitutions absolutely spot on.
At half-time I had a look at the stats, and they showed that Scotland had made 64 tackles and England had made 12. A five-to-one ratio of tackles after 40 minutes was just unbelievable.
To be honest there was a slight feeling of dread at that point because England have been able to tire other teams down in the opening sixty minutes and then take advantage later in the game. With the power England had to call on from their bench there was a real danger they could wear Scotland down as the match wore on.
But Scotland came out even stronger in the second half and, as the game wore on, they began to win some ball and England began to turn it over, which indicated that the fatigue was actually affecting the English.
The effort of the back row was absolutely outstanding, but they would be the first to pay tribute to the performance of the tight five because the weight disadvantage they were under was phenomenal.
The back row met England on the gain line and made things very difficult for the English to get any forward momentum.
Scotland now face two tough games away from Murrayfield and I'm sure neither Ireland nor Italy will be easy.
But the great thing is that we are talking about Scotland as contenders for the championship once again, and even I didn't think we'd be doing that at this stage of the competition.
England flanker James Haskell insists he will be pushing as hard as possible to be back from a toe injury in time to make his case for a spot in Eddie Jones' side looking to defend their RBS 6 Nations title next year.