U.S. Open 2025: Aryna Sabalenka into second round, Novak Djokovic off the mark

World number one Sabalenka, who is bidding to become the first woman to claim back-to-back U.S. Open titles since Serena Williams completed a hat-trick of wins in 2014, was made to work hard en route to a 7-5, 6-1 victory over Rebeka Masarova