Day four of the US Open is already upon us and the two defending champions have continued their progress in New York. Overnight, Novak Djokovic was leading Laslo Djere 6-4 6-4 2-0 when an abdominal issue forced his compatriot to retire.

Coco Gauff also sailed through, beating Germany's Tatjana Maria 6-0 6-0. But there was heartbreak for Britian's Harriet Dart, wholost to Ukrainian 19th seed Marta Kostyuk.

The British No.3, aiming to reach the third round for the first time in her career, was way below her best as a series of unforced errors signified her 7-6 (12-10) 6-1 defeat. In sweltering heat, the 28-year-old cut a disconsolate figure afterwards.

The last three remaining British singles players, Katie Boulter, Jack Draper and Dan Evans are all in action today. With play starting at 4pm UK time, Katie Boulter takes on Spanish world No.74 Jessica Bouzas Maneiro in the second match.

Jack Draper then faces Argentine world No.64. Facundo Diaz Acosta. And ffter winning the longest match in US Open history in the first round, Dan Evans will then play the last match of the day against Argentine world No.36 Mariano Navone.

The two top seeds meanwhile, Jannik Sinner and Iga Swiatek, are also playing in the day session in the Arthur Ashe Stadium.