I would first like to point out that I don't know the exact origin of the expression, but I bet Brünhilde is in there somewhere.
Secondly, I'd like to welcome Rubrick back into our throng after his sojourn to the tropics.
Now, then.
Think about this: In what sport, anywhere in the world (except perhaps at Hogwarts Academy of Witchcraft and Wizardry; I'm not far enough along in the Harry Potter series yet to know and defer to Jo aka jmh for elucidation on that point) do fans hang around after a game to sing a national anthem?
In this US of A, the national anthem is sung BEFORE the first pitch, after which you can often hear a resounding "Play Ball!" emanating from the stands. Rubrick, perhaps you're confusing your story with the quote attributed to the great Yogi Berra: "It ain't over till it's over." (and as for your American friends, best stick with me kid, I won't steer ya wrong