Djokovic lost the first two sets in the quarterfinal 6-4 6-4, then called it quits with a back injury.

Afterward, he wasn't overly impressed with the clay-court game of Nadal, despite him being the defending champion at Roland Garros and carrying a 53-match winning streak on the surface into the year's second grand slam.

The Serb employed phrases such as Nadal "was not feeling too comfortable," "I don't need to play anything special" to beat the Spaniard and "he's not unbeatable" on clay -- which didn't exactly endear him to tennis fans.

Nearly a decade later, Djokovic has matured and -- being a global superstar -- done so in the public domain.

He is well spoken in five languages, goes to great lengths to ensure his body is in peak condition, and retirements are a thing of the past. Only the harshest of critics would suggest the world No. 1 is not a fine ambassador for the sport.

Once considered nigh on impossible, he interrupted the Nadal-Roger Federer duopoly.

Yet there's one thing Djokovic has yet to accomplish in his career -- and that's defeat Nadal at the French Open.

For many, his finest opportunity comes Wednesday, with a victory potentially paving the way for a title that would allow Djokovic to complete the career grand slam, emulating Federer and Nadal.

With Nadal owning 14 grand slam titles, nine of them in Paris, and Djokovic boasting eight majors, it's one of the highest-profile quarterfinal matchups in grand slam history, mirroring Pete Sampras' tussle with Andre Agassi at the 2001 U.S. Open. That one lived up to the hype, Sampras triumphing in four sets -- all tiebreaks.

A loss of form from Nadal, combined with French Open organizers not bumping up his seeding from sixth, led to the possibility of the two titans clashing in the last eight, and the 25% chance materialized in the draw.

"I'm supporting Rafa in protest of the stupidity of the tournament for not seeding him No. 2," Brad Gilbert, the former coach of Agassi and Andy Murray, told CNN this week while wearing a black windbreaker emblazoned with Nadal's bull logo.

The last time Nadal and Djokovic played sooner than the semifinals at a non round-robin event was in Rome in 2007, when the former hadn't captured any grand slams outside Paris and the Serb didn't have any majors at all. Rihanna's "Umbrella" would soon rule the charts and Twitter was mostly for the birds.

Their rivalry has now reached historic proportions -- no two men in the Open Era have faced off as regularly.

Nadal leads 23-20 overall -- and is, crucially as it relates to Wednesday, 6-0 at the French Open.

He improved to 70-1 at the French Open following Monday's fourth-round win over young American Jack Sock, with his lone blemish coming in 2009 against Robin Soderling.

The closest Djokovic came to unseating Nadal was in the 2013 semifinals, when a rare infringement of the rules by the Serb helped the left-hander win 9-7 in the fifth.

Djokovic has so far failed to turn wins over Nadal at French Open warmups in Monte Carlo, Rome and Madrid into the ultimate success in Paris, where the best-of-five set format favors the Mallorcan.

But for Gilbert and others, Djokovic's time is now.

Of seven former players turned tennis broadcasters at U.S. network ESPN, Gilbert and two others picked Djokovic to lift the winner's trophy. Only two chose Nadal.

The head of the French Tennis Federation appears to be rooting for Djokovic, too. Jean Gachassin -- never shy to turn cheerleader when watching matches despite his senior role -- reportedly told Djokovic on Monday when the two shook hands, "It's the time -- you deserve it."

"I liked Djokovic at the start of the tournament and I still like him," said Gilbert, who achieved a career high of No. 4. "Judging just how good Novak is, if someone is going to do it, it's because of the way he's playing tennis. Soderling did it, but that was just one day.

"Djokovic is just clearly an amazing clay-court player."

While Nadal dropped a set to Sock, Djokovic has won all 12 sets he has played this fortnight. His latest victim was France's Richard Gasquet, who claimed a mere six games Monday.

(CNN)