Aryna Sabalenka, of Belarus, reacts after defeating Polina Kudermetova, of Russia, during the second round of the U.S. Open tennis championships in New York.

Polina Kudermetova, of Russia, reacts after losing to Aryna Sabalenka, of Belarus, during the second round of the U.S. Open tennis championships in New York.

Aryna Sabalenka, of Belarus, hugs Polina Kudermetova, of Russia, after their second round of the U.S. Open tennis championships in New York.

Polina Kudermetova, of Russia, leaves the court after losing to Aryna Sabalenka, of Belarus, during the second round of the U.S. Open tennis championships in New York.

Aryna Sabalenka, of Belarus, returns a shot against Polina Kudermetova, of Russia, during the second round of the U.S. Open tennis championships in New York.

Polina Kudermetova, of Russia, returns a shot to Aryna Sabalenka, of Belarus, during the second round of the U.S. Open tennis championships in New York.

Aryna Sabalenka, of Belarus, serves against Polina Kudermetova, of Russia, during the second round of the U.S. Open tennis championships in New York.

Polina Kudermetova, of Russia, returns a shot to Aryna Sabalenka, of Belarus, during the second round of the U.S. Open tennis championships in New York.