Aryna Sabalenka launched the defense of her US Open crown with a 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.

Aryna Sabalenka and Novak Djokovic overcame early tests to reach the U.S. Open second round before the Grand Slam descended into chaos late on Sunday when Daniil Medvedev launched a tirade at the match umpire and fans disrupted his opponent's service game.