The Serbian can still win the tournament, which remains in the roudn-robin stage.
The 22-year-old Italian won a three-hour marathon 7-5 6-7 (5) 7-6 (2).
How does Novak Djokovic stay motivated? Plus, another perspective on Coco Gauff's U.S. Open speech.
Goran Ivanisevic's son made an adorable cameo, too, in the Turin clip where candy, doubles partners and Santa Claus came up.
Djokovic has been jeered by some inside venues at recent tournaments but that will likely motivate the World No 1 to raise his performance at the ATP Finals ...
Eurosport is your source for the latest ATP Finals match updates. Get the full recap of Novak Djokovic - Hubert Hurkacz, complete with stats and highlights.