ABU DHABI, Dec. 28, 2018  Dominic Thiem of Austria competes during his match against Karen Khachanov of Russia at the 2018 Mubadala World Tennis Championship in Abu Dhabi, the United Arab Emirates (UAE), on Dec. 27, 2018. Dominic Thiem lost 0-2. (Credit Image: Â© Xinhua via ZUMA Wire)