Sloane Stephens beat compatriot and friend Madison Keys in a repeat of the 2017 US Open women's singles final in the first round today ©Getty Images

Picture Gallery

Britain's Andy Murray, a former US Open champion, was involved in an epic five set tussle with Stefanos Tsitsipas, which the Greek player edged in just under five hours ©Getty Images
Britain's Andy Murray, a former US Open champion, was involved in an epic five set tussle with Stefanos Tsitsipas, which the Greek player edged in just under five hours ©Getty Images
Last year's women's singles runner-up Victoria Azarenka dropped just four games on her way to round two ©Getty Images
Last year's women's singles runner-up Victoria Azarenka dropped just four games on her way to round two ©Getty Images
John Isner of the United States changes shirts during his defeat to compatriot Brandon Nakashima ©Getty Images
John Isner of the United States changes shirts during his defeat to compatriot Brandon Nakashima ©Getty Images
Garbine Muguruza battled through in two tiebreak sets against Donna Vekic ©Getty Images
Garbine Muguruza battled through in two tiebreak sets against Donna Vekic ©Getty Images
Bulgaria's Grigor Dimitrov ends up in the crowd during a rally in his match with Sam Riffice, which he won in straight sets ©Getty Images
Bulgaria's Grigor Dimitrov ends up in the crowd during a rally in his match with Sam Riffice, which he won in straight sets ©Getty Images
Dayana Yastremska of Ukraine was edged out in a final set tiebreak by 16th seeded Angelique Kerber ©Getty Images
Dayana Yastremska of Ukraine was edged out in a final set tiebreak by 16th seeded Angelique Kerber ©Getty Images
Spectators at Flushing Meadows were required to present proof of their vaccination status in a late change to entry rules ©Getty Images
Spectators at Flushing Meadows were required to present proof of their vaccination status in a late change to entry rules ©Getty Images