Highlights of 2018 Mubadala World Tennis Championship

Spectators watch the match between Novak Djokovic of Serbia and Karen Khachanov of Russia during the 2018 Mubadala World Tennis Championship in Abu Dhabi, the United Arab Emirates (UAE), on Dec. 28, 2018. Novak Djokovic won 2-0. (Xinhua/Mahmoud Khaled)