Day 5, second Ashes Test. Not so much because Australia won or that they took a 2-0 lead in the oldest cricket contest in history. But because Test cricket, the staid old five-day, all-white game which spawned ODIs and - more recently - the Twenty20 cash cow, proved that every session in the 10 days of the first two five-day games could provide more twists than a pretzel.
Fortunes in the long-form game turn sharply on two key skills - bowling to dismiss a side rather than merely containing their batsmen; and patiently building a long innings rather than smashing the ball around the park.
The first Test match between England and Australia was played in 1877, so it's fitting that the oldest rivals in international cricket should remind us of this.