The beauty about sport is we never know what might happen when we arrive at a stadium or turn on our television.
But one thing comes as close to sporting certainty as anything else we have seen over the past 13 years: Rafael Nadal winning the French Open.
"Some say beating Rafa over five sets on clay is the toughest thing in sport - not just tennis," says seven-time Grand Slam singles champion John McEnroe. "I would agree with that."
Since making his debut as a talented teenager in 2005, Nadal has won a record 10 singles titles at Roland Garros - no-one in the men's game has managed to win as many at the same Grand Slam.