Aryna Sabalenka launched the defence of her US Open crown with victory Sunday while Novak Djokovic made a successful start to his latest bid for a record 25th Grand Slam singles title but a raging Daniil Medvedev exited.
World number one Sabalenka, bidding to become the first woman to claim back-to-back US 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 Switzerlands Rebeka Masarova.
Masarova, ranked 108th in the world, pushed Sabalenka out of her comfort zone with a gutsy performance on the Billie Jean King National Tennis Centers main Arthur Ashe Stadium showcourt.