Australian Nick Kyrgios has admitted he was bitterly disappointed to withdraw from the US Open after struggling with a hip injury on Saturday night.

The 14th seed had looked in good form this week at Flushing Meadows and appeared to be on his way to another victory before he started to struggle against Illya Marchenko.

He claimed the opening set 6-4 but then began to rub his hip after making some brilliant shots.

Kyrgios was forced to take a medical timeout after losing the second with Marchenko winning six straight games at one point.

The 21-year-old asked for another break at 4-1 down in the third set and tried to carry on before losing another two games.

He eventually conceded defeat in the third-round clash and the Canberra-born star admitted he had struggled with his hip for the last few days.

“It’s tough, I don’t like to retire, that is probably the second or third time I’ve done it,” he told reporters.

“I’ve got a lot of belief in my game to still win matches when I’m not feeling great but his (Marchenko’s) strength is to make balls and move me around, it’s not great.

“To be fair, my hip was bothering me my first two matches and I got through, so I guess it was just a matter of time.”

Kyrgios had been hoping to challenge the world’s top players this year but world number one Novak Djokovic remains on course to win another Grand Slam at odds of 2.38.