Bianca Andreescu, of Canada, reacts after defeating Greet Minnen, of Belgium, during the third round of the US Open tennis championships, Saturday, Sept. 4, 2021, in New York. (AP Photo/Seth Wenig)

Novak Djokovic, of Serbia, returns a shot to Talon Griekspoor, of the Netherlands, during the second round of the US Open tennis championships, Thursday, Sept. 2, 2021, in New York. (AP Photo/Frank Franklin II)

Belinda Bencic, of Switzerland, reacts during the third round of the US Open tennis championships against Jessica Pegula, of the United States, Saturday, Sept. 4, 2021, in New York. (AP Photo/Seth Wenig)

Maria Sakkari, of Greece, reacts after scoring a point against Petra Kvitova, of the Czech Republic, during the third round of the US Open tennis championships, Saturday, Sept. 4, 2021, in New York. (AP Photo/John Minchillo)