2017 US Open kicks off in New York City

Alexander Zverev of Germany serves to opponent Darian King of Barbados during their opening round match at the U.S. Open tennis tournament in New York, Tuesday, Aug. 29, 2017. [Photo: AP/Kathy Willens]

Darian King, of Barbados, reacts after losing a point to Alexander Zverev, of Germany, during the first round of the U.S. Open tennis tournament, early Tuesday, Aug. 29, 2017, in New York. [Photo: AP/Julio Cortez]

Maria Sharapova reacts after defeating second seed Simona Halep of Romania, 6-4, 4-6, 6-3 in their opening round match in the U.S. Open tennis tournament in New York, Monday, Aug. 28, 2017. [Photo: AP/Kathy Willens]

Simona Halep, of Romania, returns a shot to Maria Sharapova, of Russia, during the first round of the U.S. Open tennis tournament, Monday, Aug. 28, 2017, in New York. [Photo: AP/Julio Cortez]

Jordan Thompson, of Australia, returns a shot to Jack Sock, of the United States, during the first round of the U.S. Open tennis tournament, Monday, Aug. 28, 2017, in New York. [Photo: AP/Julio Cortez]