Novak Djokovic lost his momentum in the second half of last season and was toppled as the world number one by Andy Murray because his work-rate dropped, the Serbian’s former coach Boris Becker said yesterday.

Speaking a day after the two terminated their cooperation by mutual consent, German Becker said Djokovic’s need to spend more time with his family had derailed him on the court.

“He didn’t spend as much time on the practice court in the last six months as he should have and he knows that,” said Becker, who helped Djokovic to six grand slam titles after they teamed up in December 2013.

“Success like this doesn’t happen by pushing a button,” he told Sky News.

“The profession of a tennis player is probably the most selfish one in sports because it has to be about you and he is the first to say he is a family man, so of course his wife and the rest of his family had to take back seats.

“They don’t spend enough time together. I had it too, 20 years ago. It is just the nature of the beast, being a tennis player.”

Having completed a career slam when he won his maiden French Open title in June, Djokovic suffered an astonishing loss of form.

He crashed out of Wimbledon in the third round to Sam Querrey and made a first-round exit at the Rio Olympics at the hands of Juan Martin Del Potro.

Djokovic then lost the US Open final to Stan Wawrinka, a defeat Becker said was a massive psychological blow to the Serb.

“I know the US Open loss in the final against Stan hurt,” he said.

“I think that is what he needed maybe in a funny way was to lose a little bit, to realise what it is like to lose, because he hasn’t been losing for two-and-a-half years.

“But Novak has got to go back to work and train hard.

“He has to go back to the office and practise these hours and refocus on what made him strong in the first place.”