For the third-straight year, Novak Djokovic will get a much-sought opportunity to end the dominance of Rafael Nadal at Roland Garros and in doing so collect the one Grand Slam title he has yet to win.

It is a rivalry that has become the dominant one not just of this era, but in the history of tennis. The pair will meet for a record 42nd time in the French Open final on Sunday, and for Djokovic the stakes may never have been higher. Not only would a win give him a career Grand Slam, but it would send him above Nadal to the top of the rankings.

To do so, the Serbian will also have to overcome his greatest challenge. While Djokovic has beaten his greatest rival in the final of all three of the other Grand Slams, conquering Nadal on clay over five sets has proved too high a hurdle in each of the last two years. In the final of 2012, Nadal prevailed in four sets before in last year’s semifinals -- when Djokovic was predicted to have his best chance against an opponent who was in his first Grand Slam since missing seven months with a knee injury -- Djokovic got agonizingly close before going down 9-7 in the final set. A smash that Djokovic blundered when up a break in the final set will surely remain firmly imprinted in his memory until he wins at Roland Garros. Djokovic, though, is using that narrow loss as an instrument to fuel his belief.

“We played some really close and good matches, good quality matches the last two years here, especially the one last year serving at 4-3 in the fifth set to go 5-3,” he said, reports the official French Open website. “It was a very close one. And knowing that I was that close to win against him the past two years gives me that reason to believe that I can make it this time,” Djokovic said. “It's easier said than done, of course … but he's not unbeatable.”

Certainly Nadal has looked more vulnerable on clay this year than in the buildup to any of previous nine visits to Roland Garros, which have yielded an extraordinary eight titles. The Spaniard lost early in both Monte Carlo and Barcelona -- two tournaments he has previously dominated -- before being helped by an injury to Kei Nishikori to come back and win the final in Madrid. In the final tournament before Paris, Djokovic bested Nadal in the final of Rome. That was the fourth straight time that Djokovic came out on top against Nadal, while he has also been in superb form at Roland Garros -- dropping just two sets on his way to the final.

“I don't know how much upper hand I have, really,” Djokovic said. “You have to take in consideration the results that he had in Roland Garros and that I had in my career,” Djokovic said, “I think there is no doubt that he is the favorite to win the title there. But, OK, I have been playing some good tennis … Rome a few weeks ago against him in the final definitely gives me confidence and hopefully self-belief before our match.”

While not having enjoyed ideal preparation, Nadal’s belief should also be strong after his performances in the past two weeks. The 28-year-old has dropped just one set on route to the final -- the opener against compatriot David Ferrer in the quarterfinals. He went onto steamroll Ferrer and then did likewise in the semifinals against Andy Murray. Ferrer’s comments after his quarterfinal when one of the biggest fighters on the tour admitted to fading away due to the sheer mental challenge of trying to overcome Nadal in five sets on clay spoke volumes. Only one man has ever done it -- Robin Soderling, in 2009.

“He beat me [the last] four times but he never beat me here” Nadal said of Djokovic. “It's true that I prefer to be in a position that I beat the opponent that I’m going to play four times than in the other position. Probably he will come to the match mentally a little bit better than me because he beat me in the last four. But at the same time, my feeling is I am doing things better and I am playing better again, so that's a positive feeling for me.”

While Djokovic has a massive amount at stake in the match, so too does Nadal. Not only can he further cement his legacy as the greatest clay-court player of all time, but a victory would take him level with Pete Sampras with 14 Grand Slam titles and leave him just three behind the record 17 of Roger Federer.

“Novak already has a lot of times positive results here. It's nothing new for him to be in the final,” Nadal explained. “He has the motivation to win Roland Garros for the first time for sure. But at the same time, he has the pressure to win for the first time. I have the pressure that I want to win and the motivation that I want to win the ninth. So I don't see a big difference in that. I'm going to go on court with the same motivation as him.”

Prediction: As always between these two, the key battle will between whether Nadal’s forehand or Djokovic’s backhand will dominate. Nadal will look to hit as many inside-out forehands as he can and will be helped substantially in that regard by the warmer conditions after two chilly weeks in Paris. That was true in his semifinal victory over Murray when Nadal played perhaps his best clay-court match of the year to date.

But Djokovic gives Nadal more problems than any other player on clay because of the ability of his two-handed backhand to deal with Nadal’s rasping left-handed forehand. Djokovic has the best down-the-line backhand in the sport and his ability to hit there to Nadal’s backhand, while also surprising him with short crosscourt angles, will be key.

It is hard to imagine anything other than another grueling five-set epic, where both players’ incredible physicality and stamina will again come to the fore. Still, Djokovic could find the task of beating Nadal in five sets on clay an unscalable mountain.

Nadal in five sets.

Where to watch: The men’s French final will get underway not before 9 a.m. ET. Coverage will be provided by NBC, with a live stream available on NBC Sports Live Extra