Highlights of ATP Finals tennis tournament

Stefanos Tsitsipas hits a return during the group stage match between Stefanos Tsitsipas of Greece and Holger Rune of Denmark at ATP Finals tennis tournament in Turin, Italy, on Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Stefanos Tsitsipas hits a return during the group stage match between Stefanos Tsitsipas of Greece and Holger Rune of Denmark at ATP Finals tennis tournament in Turin, Italy, on Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Holger Rune hits a return during the group stage match between Stefanos Tsitsipas of Greece and Holger Rune of Denmark at ATP Finals tennis tournament in Turin, Italy, on Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Stefanos Tsitsipas reacts after quitting the group stage match between Stefanos Tsitsipas of Greece and Holger Rune of Denmark at ATP Finals tennis tournament in Turin, Italy, on Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Jannik Sinner hits a return during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Novak Djokovic hits a return during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Novak Djokovic hits a return during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Novak Djokovic serves during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Jannik Sinner hits a return during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)

Novak Djokovic hits a return during the group stage match between Novak Djokovic of Serbia and Jannik Sinner of Italy at ATP Finals tennis tournament in Turin, Italy, Nov. 14, 2023. (Photo by Alberto Lingria/Xinhua)