2021 Davis Cup Finals semifinal: Croatia vs. Serbia

Novak Djokovic of Serbia hits a return to Marin Cilic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic (top R)/Filip Krajinovic (top L) of Serbia compete against Nikola Mektic (bottom R)/Mate Pavic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic (top R)/Filip Krajinovic (top L) of Serbia compete against Nikola Mektic (bottom L)/Mate Pavic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Marin Cilic of Croatia competes against Novak Djokovic of Serbia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic of Serbia hits a return to Marin Cilic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic of Serbia competes against Marin Cilic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic of Serbia reacts during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic (R) of Serbia competes against Marin Cilic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)

Novak Djokovic of Serbia hits a return to Marin Cilic of Croatia during the 2021 Davis Cup Finals semifinal between Croatia and Serbia in Madrid, Spain, Dec. 3, 2021. (Xinhua/Meng Dingbo)