The Spaniard most recently won the 15th Grand Slam of his career after an unprecedented 10th French Open victory last month.
Meanwhile, Federer and Djokovic are looking for their 19th and 13th Grand Slams respectively as Wimbledon enters the third round stage.
Nadal, who comfortably defeated Donald Young in the second round on Wednesday (5 July), now faces a next generation prospect in Karen Khachanov.
The 21-year-old, along with Nick Kyrgios, Alexander Zverev and Dominic Thiem, are regarded as future stars of the sport.
However, Nadal wants those who expect these young stars to emulate what his generation achieved to lower their expectations.
"For sure he's [Khachanov] good," Nadal said, as quoted on Metro. "For sure he has chances to be in a high position of the ranking."
"Win so many Grand Slams? I tell you one thing: It's not easy. Somebody has to win Grand Slams, of course, but [it] looks a little bit easier because during this part and this moment of our sport, there is three players that won 18, 15, and 12.
"But if we look back about the history of our sport, [it] was not very long time away when [Pete] Sampras has 14, and looks like nobody is going to have the chance to increase that number. We need to appreciate these things, when we need to put everything in the right spot."
The 31-year-old went on to praise Khachanov again before adding that whichever young player improves the most in the next few years will end up being the dominant player.
"And Karen is a great player, that he has chances to win a lot," he explained. "But then there are good players out there and the player who is able to improve more during the next couple of years will have the chance to win more than others."
Nadal takes on Khachanov in a third round clash on Friday (7 July).