Perhaps it was meant to end this way: Rafael Nadal and his old rival Novak Djokovic defying insurrectionists and the ages, and now hurled together for the 55th time to decide the winner of a new team tournament still trying to pull its pants on. Anyone who might have said something about the end of an era better have ear plugs on for a while yet. Sunday’s final of the ATP Cup at Sydney’s Olympic Park promises to be the rowdiest conclusion to the new 24-nation tournament, played out by familiar faces. The fact Nadal and Djokovic are there for Spain and Serbia, respectively, makes it special. The two best players in the world have not met in this new tournament, which began 10 days ago and has gathered momentum from a low base of public recognition. But now Nadal, the world No 1, and Djokovic, just behind him, must assert themselves when Spain play Serbia in a packed house at the Ken Rosewall Arena. When Nadal beat the energetic Australian Alex de Minaur, 4-6, 7-5, 6-1, in the concluding singles of the second semi-final, it was a tough blow for the young Australian, but he took it well. “I…