I was recently watching Harry Potter (because I'm super-cool), and it occurred to me: has there ever been a sport that had something akin to catching the snitch in Quidditch, where the game immediately ends in victory, regardless of how long you've been playing or how well you've been doing?
All sports I can think of generally end after a certain period of time (e.g. basketball), a certain number of turns (e.g. innings in baseball), or a certain number of milestones (e.g. holes in golf). With all of them, though, victory is the result of earning points as you go, so the winner can be predicted with increasing certainty as the session progresses. There may be a 9th-inning rally, but even if you turn it around in the last 2 minutes, you still have to close the distance and eventually overtake your opponent's score before you win.
Non-physical games often have instant-win conditions (e.g. checkmate in chess) where you could be doing horribly and then instantly be the winner, but are there any (or have there been any in history) physical sports that have similar potential? I seem to recall that the ball game of the Aztecs had something like this, but the accounts I'm finding online seem to disagree with each other.