After an outstanding season, the world No 1 appears to have reached his limit after managing barely any tennis since September due to injuries.
Novak Djokovic is running on fumes
It is not inaccurate to suggest that Novak Djokovic fell to pieces after nine months of some of the most brilliant tennis we have seen, his body betraying him after a long run of meeting and beating the best players on the planet.
On September 12, the world No 1 won the US Open, his third major championship of the year. Six days later he attempted one Davis Cup semi-final match for Serbia but retired in the second set … and has hardly been seen since.
He missed six weeks with what was described as a back injury; that cost him the whole of the Asian portion of the ATP schedule.
He returned for the Swiss Indoors Basel but succumbed in the semi-finals to Kei Nishikori, someone Dvokovic might have easily dispatched six months earlier. Clearly, he was not quite right.
Last week, his right shoulder throbbing, he laboured through two matches at the Paribas Open, making 44 errors in an ugly victory over Viktor Troicki, then withdrew, saying, "my body is aching for recovery".
His detractors suggested he had shown up in Paris for a US$1.6 million (Dh5.88m) payday, never intending to stay long. Djokovic would have been ineligible for his share of a bonus pool had he missed consecutive Masters event, and he had not played in Shanghai last month.
That he lasted two matches, including that three-set grind with Troicki, would seem to indicate he wanted to play.
In a statement Djokovic released before pulling out of a quarter-final with Jo-Wilfried Tsonga, he said: "I have pushed myself to the limit by playing, and after the match yesterday my shoulder got worse … I have to put my health first and withdraw even though my urges as a professional player are making me want to play until the last drop of energy."
He apologised to fans holding tickets to the quarter-final, and added: "My season has been long and tiring, I played all of my matches at my highest level, and now my body is aching for recovery."
Fans are left to ponder whether Djokovic is somehow injury prone; Roger Federer managed to go through season after season at an elite level without breaking down.
Another topic that aficionados may wish to discuss: has the strain and exertion in matches among elite players reached some point of no return for their near-term health?
Djokovic is top-seeded for the season-concluding ATP World Tour Finals in London next week, but whether he is up to competing against the seven other men in the top eight is open to question.
Certainly, Janko Tipsarevic, the first alternate, will want to keep his mobile switched on.