World number one Murray's 2017 has been plagued with injuries and poor form despite winning the Dubai Open for the first time.
The Briton, who revealed that he would have done things differently such as taking more time off a busy schedule after becoming the top ranked player in tennis, crashed out of the Monte-Carlo Masters and most recently, the Barcelona Open after losing to Dominic Thiem.
Meanwhile, world number two Djokovic, whose only title this year was in Qatar, has not had the best year either with a 14-4 record that saw him crash out of the 2017 Australian Open in the second round.
The Serbian ace was also knocked out of the Mexican Open, BNP Paribas Open and Monte-Carlo Masters. Nadal however, who won in Monte-Carlo and Barcelona, believes the two top ranked players will come back sooner rather than later.
"They will be at their best level again," Nadal said, as quoted on TennisWorldUSA. "If they are world no. 1 and 2, there is a reason. If it won't happen in the next events, it will be in the following ones, and if it won't be like this, it will happen after. They will be back more soon than later, unfortunately for me."
The Spaniard is not afraid of any opponent though, as 2017 has been very successful for him, having already reached five finals and remaining unbeaten during the clay season.
"I am happy with my two titles won, and after two very good weeks now I work to be in the best condition heading in Madrid, Rome and Paris," he added. "I am doing well and my goal is that my level keeps being high."
"I would like to fight to win Roland Garros, it can happen anything. However, winning in Monte Carlo and Barcelona are more than enough at the moment for me."