Certainly, there have been rumours that his marriage has been in trouble for at least 18 months, with wife Jelena’s stony face at the US Open last summer said to tell its own glum story.
Footage released of the two of them bickering over a Facebook video in February only tends to reinforce the impression that there is trouble in paradise. (He chided her for the angle at which she shot the footage of him training, and she bitterly asked where his manners were, adding: ‘Thank you love, thank you’. Isn’t that the way to say it?’)
And now BBC commentator John McEnroe has brought the talk of personal issues to public attention, rightly or wrongly comparing the 30-year-old champion with troubled golfer Tiger Woods.
Speaking about Djokovic’s period of poor form, McEnroe said Djokovic ‘had some off-court issues with the family,’ adding: ‘That’s going to throw you. If you’re distracted, you’re not the same player.’
He went on: ‘The person that comes to mind immediately with Novak is not a tennis player, it’s actually a golfer: Tiger Woods.
‘When [Woods] had the issues with his wife and then he seemed to go completely off the rails and has never been even close to being the same player.
‘So we’re starting to say: ‘Wait a minute, is this possible with him?’ I think there’s a big difference, one is the age, but two the health. I think this isn’t a physical thing, this is more a mental thing.’
The Italian newspaper Gazzetta dello Sport even claimed last summer that a divorce was on the cards.
But surely comparisons with notorious womaniser Woods are far-fetched?
While Djokovic is far from any mea culpa, he has confirmed that his poor form at Wimbledon last year was the result of off-court dramas.
Last year he was surprisingly knocked out in the third round by Sam Querrey, and then pulled out of Serbia’s Davis Cup tie against Great Britain, explaining that he needed to spend time with his family.