But, considering Nadal has gone 21-2 this year (including three singles titles), he shouldn't feel too bad right about now.
Keep in mind, after missing the second half of the 2012 campaign with tendinitis, Nadal has defied a lot of people's expectations. He may be 26 years old, but the wear and tear on his body throughout the years is hard to ignore.
The fact that he's won three singles titles already this year is frankly unbelievable, especially considering he's won against top players Roger Federer, David Ferrer, Tomas Berdych, Juan Martin Del Potro and Jo-Wilfried Tsonga along the way.
After congratulating Djokovic on Sunday, Nadal said, via CNN: "Last year was especially hard for me, but I had the support of my team and my fans. That was a very positive energy for me and gave me motivation to play here again."
Nadal had won the Monte Carlo Masters in his last eight appearances (an ATP record for a tournament) before Sunday's loss, and this must have been a tough pill for him to swallow. But he needs to stay positive. His body may not respond the way it used to, but if he loses the mindset that has propelled him to 11 Grand Slam singles titles throughout his career, he loses everything.
Even at the Monte Carlo Masters, it was unrealistic to think Nadal would defeat Djokovic this year, given his road back from injury. Beating the 31-year-old Federer is one thing, but beating the young No. 1 is a different story.
Still, that's not to say Nadal can't defeat Djokovic at a later date, specifically at the upcoming French Open, where Nadal has notched a record seven titles.
Nadal said after the loss on Sunday, via ESPN: "Of course, I want to win Roland Garros. That's no secret. But I need to keep on having the right positive mindset."
Tennis is both physical and mental. Nadal may have lost some of his athleticism, but he can still have his mental game. And that's a very powerful thing on the court. There is still hope for the historic Rafael Nadal to win the French Open this year.