NEW YORK: Defending champion Aryna Sabalenka received a walkover into the US Open semifinals on Tuesday after Marketa Vondrousova was forced to withdraw from their last eight showdown due to a knee injury, organizers said on Tuesday. Vondrousova, the 2023 Wimbledon champion, had impressed in New York with upset victories over seventh seed Jasmine Paolini and ninth seed Elena Rybakina, but her run came to a painful end after she pulled up in practice earlier on Tuesday.