Heartbreak for Niland at Flushing Meadows

Top seed Novak Djokovic barely had to break sweat to make it through the second round of the US Open as Irishman Conor Niland retired through illness while trailing 6-0 5-1 at the Arthur Ashe stadium.

Niland had required attention early in the second set after apparently being ill during the warm-up, and although he soldiered on for a short while, he bowed to the inevitable as Djokovic proved far too strong.

Niland looked lost for most of the match as Djokovic swiftly got back to winning ways after losing his last appearance – against Andy Murray when he suffered a shoulder injury in the final in Cincinnati a week ago – for only his second defeat of an incredible season.

After completing a 6-0 whitewash in the opening set, Djokovic took the first game of the second too before Niland finally made a breakthrough, levelling it at 1-1 to earn a few cheers from the New York crowd.

But soon after he was receiving attention from medics and although he battled on gamely, it was clear he did not have anything like what it would take to trouble Djokovic and the injury forced him out.

Before that on the Arthur Ashe court, women's top seed Caroline Wozniacki won in straight sets against Nuria Lago-stera Vives.

Elsewhere there were wins for Victoria Azarenka and Jelena Jankovic while men's 5th seed David Ferrer booked his place in the next round along with Jo Wilfred Tsonga.

Rafa Nadal and Serena Williams are both in action after midnight.