Djokovic is looking to hold all four Grand Slam titles for the first time since he last accomplished the feat in 2015/16.
The Serbian is just five major tournament wins behind Roger Federer’s all-time record and he also has two fewer than Nadal.
Serena Williams’ coach Mouratoglou has tipped the world No 1 to find his best form and stake his claim as the greatest player of all time.
And that will start at the French open over the next fortnight.
“I think it’s going to be more difficult for Nadal to beat Federer’s record,” Mouratoglou told tennishead.net.
“In my opinion Nadal’s chances depend largely on Djokovic, because when Novak is at his best I suspect he will stop Rafa winning a lot of tournaments, including Grand Slams.
“While I believe that Rafa is the best clay-court player of all time, there have been many occasions when I’ve seen Novak take control against him on clay.
“He has beaten Rafa in finals at Monte Carlo, Madrid and Rome.”
However, Nadal has won 11 French Open titles and is a formidable force on the Parisian red dirt.
“The one place where Rafa has generally kept a hold over Novak is at the French Open, where he has won six of their seven meetings,” Mouratoglou added.
“I think Novak has sometimes struggled mentally at Roland Garros, where Rafa obviously has such an incredible record with his 11 titles.
“In most of Novak’s matches against Rafa in Paris he has not played with the same mindset as he has when they have met on clay elsewhere.
“However, Novak won their last meeting at Roland Garros, in 2015.
“I think the outcome of the French Open may well depend on matches Rafa and Novak play against each other.
“If they meet and Novak comes out on top, I think it will be difficult mentally for Rafa.
“I remember how Novak beat Rafa in all six of their meetings in finals in 2011, two of which were on clay.
“You could sense then the pressure that Rafa was under every time they met. If that happens again I would see Novak rather than Rafa as the favourite at Roland Garros.”