Novak Djokovic's former junior coach Bogdan Obradovic has revealed that the Serbian tennis star's struggle is down to his change of mentality over the last year.

The 29-year-old enjoyed a good start to the previous calendar year, having won the 2016 Australian Open defeating Andy Murray in the final. He continued his impressive run by winning the Indian Wells and Miami Masters and it was followed by a successful run at Roland Garros where he once again defeated Murray in the final.

Djokovic lost to Sam Querrey in the third round of the 2016 Wimbledon and suffered a shock first round exit at the 2016 Rio Olympics. A defeat at the hands of Stan Wawrinka at the US Open final last year was later followed by Andy Murray clinching the world number one ranking.

Now, Obradovic has revealed that Djokovic practiced less and "meditated more than hitting the ball" that has resulted in him struggling since his last major triumph at Roland Garros last year.

"In the last year he didn't practice for weeks and it's not good. It came to a point where he practiced less. Then he started with funny diets, he meditated more than hitting the ball," Obradovic told AS, as quoted by

"He doesn't have his normal routines anymore. In tennis changing racket changes your game. Imagine if you change your mentality."

"Before he shouted, now there are matches when he doesn't show any emotion. He doesn't have the competitive energy he had. He lost his energy. What do I think about the Mental guru Pepe Imaz? I knew about him a while ago.

"In a Segovia Challenger I had to coach some guys that had split with him. He was saying that he would have earned more money through mental training sessions. Preparing your mind is okay, but then you have to hit millions of balls during practice.

"I have nothing against him, but in this crucial moment for Novak, not make him practicing or make him changing diet is not good. All these mental trainers are putting him pressure in order to make him think that this is the most important thing.

"It's a disaster! If Phelps ate at his grandmother's house, he would enjoy it and would beat the World record. Novak is a great guy, but he is getting carried away from funny theories."

An elbow injury forced Djokovic to pull out of the Miami Open. He has recovered from the injury and will be part of the Serbia team that will face Spain at the 2017 Davis Cup World Group quarter-final.