For all of the many qualities contributing to Rafael Nadal�s unprecedented superiority at the French Open � the bullwhip of a high-bouncing lefty forehand, the reflex returns, the cover-every-corner athleticism, the endless energy and grit � there�s one element that stands above all the rest.

According to the opponent Nadal beat in the last two finals in Paris, anyway.

�You go into the match knowing that even your best tennis, even if you play it over three, four hours, might not be enough. I mean, if you do it, you maybe have a little chance, but you have to go to your limit on every single rally, every single point,� Dominic Thiem, who won the U.S. Open less than two weeks ago, told The Associated Press.

�That makes it not easy to go into the match,� Thiem said. �And that�s the mental part, I guess.�

When main-draw competition begins Sunday at Roland Garros, Thiem and every other player in the men�s bracket will be pursuing Nadal as the 34-year-old from Spain pursues history.

If Nadal manages to claim a 13th French Open championship � extending his own record for the most singles trophies won by anyone at any major tennis tournament � he would, more significantly, also collect his 20th Grand Slam title overall, tying Roger Federer�s record for a man.