Highlights of 2018 Mubadala World Tennis Championship

Novak Djokovic of Serbia reacts during the match against 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)