Despite the doubters, his career record clearly speaks for itself.
"I'm not a weightlifter, of course, but I do have an optimal balance between the strength and power and speed," he says. "Nothing seems to be missing, at least from my experience, I will keep on enjoying that."
But it's not just performance benefits that have encouraged the 32-year-old to cut meat from his diet, ethical and environmental reasons are also behind the dietary changes.
"...It's a lifestyle more than just a diet because you have ethical reasons as well, being conscious of what is happening in the animal world. The slaughtering of animals and farming and everything, that's obviously also a huge impact on climate change which maybe people don't talk about as much. It's more than a performance reason for me, it's a lifestyle, it's something i'm really proud of."
"Hopefully that community grows even more; hopefully I can inspire other athletes that it is possible to be plant-based."
Djokovic was a producer on the recent documentary Game Changers, joining other celebrities like Arnold Schwarzenegger, Jackie Chan, and James Cameron to advocate a plant based diet for athletes.
"I was definitely very happy to be a part of a very impressive group of people. From sport, the movie industry, different fields of life, very successful people who are eating plant-based, being healthy, happy, and successful in what they do. This is what it is all about."