Champion Novak Djokovic of Serbia celebrates with his coach, Boris Becker following his victory during the Men's Singles final match against Andy Murray of Great Britain on day fifteen of the 2016 French Open at Roland Garros on June 5, 2016 in Paris, France. [Photo/VCG]

"The last couple of years, I had some great times with him," Djokovic said, explaining that Becker taught him "from a psychological point of view, how to handle things on the tour, on and off the court."

"His contribution to the team is definitely big, and so everything works in harmony so far," Djokovic said at the time.

"How long it is going to go for, we don't know. We go year by year. So at the end of this year, we will see if he goes for another year."

After Djokovic's triumph in Paris, his season went sideways.

He was upset in the third round at Wimbledon by Sam Querrey and in the first round at the Rio de Janeiro Olympics by Juan Martin del Potro, then lost the No 1 ranking to Andy Murray last month, finishing 2016 at No 2.

With Becker in his corner, Djokovic finished 2014 and 2015 atop the ATP rankings.

Djokovic made an earlier change to his coaching team towards the end of the season with Spaniard Pepe Imaz joining him for the Paris Masters, where the four-time champ-ion fell in the quarterfinals, and for the World Tour Finals in London, where Djokovic lost to Murray.