Stefanos Tsitsipas of Greece serves during the singles quarterfinal match between Stefanos Tsitsipas of Greece and Hubert Hurkacz of Poland at the ATP Dubai Duty Free Tennis Championships 2019 in Dubai, the United Arab Emirates, Feb. 28, 2019. Stefanos Tsitsipas won 2-1 to proceed to the semifinals. (Xinhua/Mahmoud Khaled)