PARIS — Maybe it's because Novak Djokovic was only 19 at the time, young and full of bravado.
Or perhaps it's because he simply was saying aloud what he certainly hoped, but couldn't be absolutely positive, was true.
Then again, there's also the possibility that Djokovic knew he had conjured up more winners that day than his opponent, despite playing with an aching back that led the Serb to quit a few points into the third set after losing the first two.
Whatever the case, it's fascinating to go back and read Djokovic's declaration on the evening of June 7, 2006, after facing a certain guy by the name of Rafael Nadal in the French Open quarterfinals: "He's the best on this surface, but he's not unbeatable. That's for sure."
Djokovic, ranked 63rd at the time, had never been that far at a Grand Slam tournament. He hadn't faced Nadal before, either.
All these years later, their rivalry — the best tennis has to offer these days — gets a 44th installment Wednesday, exactly in the same place, and under the same circumstances, as it began: Djokovic vs. Nadal in a quarterfinal on Court Philippe Chatrier at Roland Garros.
No other two men have played each other so many times in the Open era of professional tennis, which began in 1968.
Nadal leads 23-20 overall, 14-5 on clay, 9-3 at Grand Slam tournaments, 6-0 at the French Open. They haven't met as early as a quarterfinal at any major since that very first encounter.
"Of course I don't like playing a quarterfinal against Novak, that's for sure," Nadal said, "and I hope that Novak won't like playing me in a quarterfinal."
This time, Djokovic is ranked and seeded No. 1, and carrying a 26-match winning streak.
"He's the best player of the world, without any doubt, today. Very dominant," Nadal said. "Probably everybody's with me that probably he is the favorite here."
Nadal is ranked No. 7, seeded No. 6, but he is No. 1 at the French Open, with a record nine championships and 69 victories in 70 career matches.
"Playing him here, and playing him in any other tournament in the world, is completely different," said Djokovic, who lost to Nadal in the 2012 and 2014 finals at Roland Garros.
The reason this is only a quarterfinal is that Nadal's right wrist injury and appendix surgery last season, plus poor-for-him results this year, dropped him out of the top five in the rankings for the first time in a decade.
That allowed him to be drawn into Djokovic's quarter. Tournament director Gilbert Ysern said on the day of the draw no consideration had been given to seeding Nadal higher, in a nod to his unprecedented success in Paris.
"We did not even think about it," Ysern said, "and he did not ask for it."
Here's a look at what else is happening at the French Open on Wednesday:
MURRAY VS. FERRER
Third-seeded Andy Murray is becoming something of an expert on clay. His quarterfinal opponent, No. 7 David Ferrer, has been one for years. Murray is 14-0 on clay in 2015, including his first two titles on the surface. He was 63-37 on clay before this year, a .630 winning percentage. Ferrer, the French Open runner-up two years ago, has won half of his 24 career trophies on clay, and is 303-117 for his career, a .721 winning percentage.
WILLIAMS VS. ERRANI
Serena Williams owns 66 career titles; the other seven women's quarterfinalists have a combined 36. Williams has won 19 Grand Slam singles trophies; the other quarterfinalists' total is one. The top-seeded Williams' opponent Wednesday is No. 17 Sara Errani, who was the 2012 runner-up in Paris. They've played eight matches, and Williams has won all eight, although the most recent was close: a three-setter in a Fed Cup match between the U.S. and Italy in April.
BACSINSZKY VS. VAN UYTVANCK
Switzerland's Timea Bacsinszky, seeded 23rd, has lost only 24 games en route to the quarterfinal, fewer than anyone else. Bacsinszky and Belgium's Alison Van Uytvanck, who is ranked 93rd, will both be playing in a Grand Slam quarterfinal for the first time.
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