Nadal is often seen as the man sandwiched between two different eras, the era of Federer and the era of Djokovic, but if that is the case, then he was the main rival to both the two dominant champions.
Nadal has played an incredible even 9 times against each of Federer and Djokovic in a slam final, that is a combined 18 slam finals where he faced arguably the two most dominant players in history. Rafa was the glue that kept it all together, making sure each of the two dominant champions had something all the greats need in the eras they stand....a truly worthy rival who stands as their equal.
18 slam finals is a joke. No other player has had that many. You can make an argument for Murray having 10 finals against them, but even that falls short by quite a bit.
So if Nadal didn't have his own true era, as often gets said with the numbers siding against him, then that does mean out of the true greats of the game, he is the one likely who had it the toughest as he was the one that partcipated in the most high profiled, high stakes rivalry of both their eras. 18 slam finals....