You've prepared for weeks. Months, even. You've set out on a specific training programme designed to condition you for the job at hand. You've followed it to the letter. You've played out every possible scenario in your head and how you would react to them. The night before your big day, you are as ready as you could possibly be.
Now imagine if, at every step of the way, you knew with depressing certainty that you will fail in your mission.
That is probably what facing Rafael Nadal on clay feels like. Failure is almost guaranteed.
On Sunday, Nadal claimed the Rome Open with a quite brutal destruction of long-time rival and world No 2 Roger Federer.
The Swiss must have summoned all of his considerable powers of understatement.
"I tried to play offensively, but unfortunately, I didn't have the best day," Federer said. "It didn't go the way I was hoping it to go."
Quite. The Spanish maestro's devastating 6-1, 6-3 win will leave no one in any doubt that, despite an injury-plagued 2012, he is once again the man to beat in Paris.
It is unlikely that anyone will.
Sure, as the action at Roland Garros kicks off Sunday, Nadal finds himself ranked fourth in the world. During his seven-month layoff, there were fears that knee injuries could bring an early end to his career.
Certainly, all three of his main rivals - Novak Djokovic, Federer and Andy Murray - have benefited from his absence, but any concerns about his ability to recapture his best form have now been banished.
He is back, looking fit and refreshed, and the Rome Open was his sixth tournament win in eight appearances since his return. And he lost the other two in the finals.
What other athlete can offer such dominance in their own particular field? It is tempting to say that Nadal on clay is as close to a sure thing as there is at the moment.
Perhaps Usain Bolt in the 100 metres. After that, it is slim pickings.
Even at his awesome best, Tiger Woods never provided comparable as-good-as-guaranteed success at the majors that Nadal does at the French Open.
And even within tennis, a sport that over the last two decades has provided transcendent, era-dominating players, Nadal's ownership of the Roland Garros venue remains remarkable.
Pete Sampras won Wimbledon seven times between 1993 and 2000, the perfection of the run ruined by Richard Krajicek's 1996 triumph. Federer's record-equalling seven titles on the same grass, meanwhile, have been accumulated over 10 years.
Nadal stands on seven French titles in eight years. Win the tournament this time around and he would beat the Sampras and Federer landmarks for excellence on one surface. What's more, at 26, he is more likely to add to that total on clay than Federer is on grass, if he stays fit.
Swedish legend Bjorn Borg, whose record of six French Open titles was surpassed by Nadal last year, believes that other players stand little chance against the Spaniard on this surface.
"He's incredible, he's is the best player that there has ever been on clay," Borg told the French Open's official website. "He's still the man to beat, and that will always be the case for as long as he is playing."
With Nadal becoming increasingly more selective about which ATP events he enters as a way to manage his fitness, he could be playing for a long time, indeed. Especially on that soft, red surface.
Last year, he blamed his injury woes on his heavy schedule, especially the number of events on hard surfaces. At the time, it seemed like yet another whinge by a top-ranked player suffering from burnout or loss of form. His performances since his return would suggest that he was right all along.
For his opponents, there was one glimmer of hope that Nadal's march towards an eighth title could be derailed earlier than usual; the prospect of him being seeded fifth.
But even that has been swept aside. By winning in Rome, Nadal this week moved up to fourth in the world, effectively ensuring he will not meet Djokovic, Federer or Murray in the quarter-finals in Paris. With Nadal on 36 wins out of 38 matches this year, it is likely his rivals are the ones feeling relieved at this small mercy.
"So after eight tournaments, six victories and two finals, it's a dream for me," Nadal said on Sunday.
For everyone else, the nightmare looks set to continue.