Naomi Osaka, of Japan, right, and Greet Minnen, of Belgium, greet each other after Osaka won their match during the first round of the U.S. Open tennis championships in New York.

Naomi Osaka, of Japan, reacts to winning a point against Greet Minnen, of Belgium, during the first round of the U.S. Open tennis championships in New York.

Greet Minnen, of Belgium, reacts to loosing a point to Naomi Osaka, of Japan, during the first round of the U.S. Open tennis championships in New York.

Naomi Osaka, of Japan, returns a shot against Greet Minnen, of Belgium, during the first round of the U.S. Open tennis championships in New York.

Greet Minnen, of Belgium, returns a shot against Naomi Osaka, of Japan, during the first round of the U.S. Open tennis championships in New York.

Naomi Osaka, of Japan, returns a shot against Greet Minnen, of Belgium, during the first round of the U.S. Open tennis championships in New York.

Greet Minnen, of Belgium, return a shot against Naomi Osaka, of Japan, during the first round of the U.S. Open tennis championships in New York.

Naomi Osaka, of Japan, serves to Greet Minnen, of Belgium, during the first round of the U.S. Open tennis championships in New York.