This is not the first time Djokovic has named the 21-time Grand Slam champion his greatest rival. It's no surprise really, considering they've faced off 58 times on the tennis court -- the most of any pair in ATP history.
But the interesting thing is that Nadal possibly doesn't feel the same way. The Mallorcan has maintained time and again that his arch-rival is in fact Roger Federer. The pair have crossed swords 40 times to date, with 24 of those contests going in favor of the Spaniard.
The Swiss has also described the Spaniard as his biggest rival, despite having played more matches against Novak Djokovic (27-23 in favor of the Serb). Going purely by the numbers, it seems like they are just mistaken.
With a little context, however, things become clearer. When Rafael Nadal burst onto the scene in 2005, Roger Federer was the man to beat. He was the World No. 1. He had won four Grand Slams at that point and was one Roland Garros title short of the elusive Career Slam.
Although he lost at three French Opens to Nadal between 2005 and 2007, he was still considered unbeatable at the other three Slams. The Mallorcan, then seen as more of a claycourt specialist than the all-courter he is now, had to overcome the Swiss at every turn to prove his mettle.
Consider this: between 2006 and 2008, the duo faced each other 15 times (10-5 in favor of the Spaniard). Nine of those encounters came on clay, out of which the 40-year-old won one.
That was why when the 21-time Grand Slam champion prevailed over Federer in the final of the 2008 Wimbledon to win his first non-clay Slam, it was the biggest moment of his career at the time. To this day, it is still considered by many to be THE moment that signaled the rise of Nadal into the champion he is today.
It was a victory Nadal badly needed and fully deserved. To prevail over the five-time defending champion on the very surface he had made his own transformed him into something more. Possibly because that win came against Federer, the 35-year-old could not help but think of the Swiss as his greatest rival.
Yes, Nadal has played more often against Djokovic in the years since. The "Djodal" rivalry is also extremely evenly matched in terms of skill, technical prowess, grit, and everything else.
But rivalries are more than just numbers. They have to be. They are just as much psychological, if not more, than statistical. And the fact that the Mallorcan's definitive achievement came against Federer is undeniable.
In turn, the Swiss had to prove himself over and over again against a player who was five years younger at a time when there was no one else to challenge his authority. Sure, Federer was already in line to become a GOAT candidate before he met the Spaniard, but the World No. 4 was the perfect foil to showcase his greatness in a way that would have been impossible otherwise.
The 20-time Grand Slam champion's encounters with Djokovic over the years have been just as intense. Unfortunately, they came too late in his career.
Novak Djokovic's definitive victories came against Rafael Nadal
To explain why Novak Djokovic considers Rafael Nadal his greatest rival, we need to identify where his career-defining victory arrived? The World No. 1's first Slam title came at the 2008 Australian Open, where he disposed of Roger Federer in the semifinals.
His second Major title, at the 2011 Australian Open, saw him vanquish Andy Murray in the final. But following that, the Serb met the Mallorcan in 11 straight finals between 2011 and 2013, out of which he won seven.
Three of those victories came in Slam finals, with Djokovic notching up his third, fourth and fifth Major titles at the 2011 Wimbledon, the 2011 US Open and the 2012 Australian Open respectively. The last of those was a marathon five-setter that is considered one of the greatest matches played in the history of the sport to this day.
It was a match Nadal referred to as "the greatest loss" of his career, meaning that it could also qualify as the greatest win of Djokovic's career. The 20-time Grand Slam champion has been involved in more important matches, of course, but none of them may have been possible without the mental boost he got from beating the Mallorcan in Melbourne.
Rafael Nadal, therefore, acts as a bridge between two of the greatest players in the history of tennis. For both Novak Djokovic and Roger Federer, he is their greatest rival. He was the one who pushed both to the edge and demanded that they take their levels up another notch.
For what it is worth, we may never get an objective answer to decide who the GOAT is. There will always be people who prefer one over the other for a variety of reasons that are not always logical. But no matter what, it should not be forgotten that it was Rafael Nadal who pushed the prime versions of Djokovic and Federer to hit new heights.
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