Japan's Naomi Osaka hits a serve agasinst Coco Vandeweghe of the United States in their first-round match at the U.S. Open tennis tournament at the Flushing Meadows in New York on Aug. 29, 2016. The 18-year-old Osaka won her debut game with 6-7 (4-7), 6-3, 6-4. ( The Yomiuri Shimbun via AP Images )