World number two and second seed Andy Murray has pulled out of the US Open after being forced to concede defeat in his battle with a long-standing hip injury.

Murray joins current title holder Stan Wawrinka, Novak Djokovic, and Kei Nishikori on the sidelines, leaving a decimated men's draw and the old guard of Rafael Nadal and Roger Federer to shoot it out in the semis.

Murray revealed he had first felt the injury after his semi-final loss to Wawrinka at the French Open back in June.

It further reduced his powers at Wimbledon, where he fell to unfancied 24th seed Sam Querrey in five sets at the quarters.

And, although playing would not have aggravated the problem further, he's taken the gut-wrenching decision to pull out of the upcoming Grand Slam, after revealing: "It's too sore for me to win the tournament. Ultimately that's what I was here to try and do."

A one-time winner at Flushing Meadow, in 2012, Murray flew out to New York on August 18 in preparation, and even told a press conference: "I was actually practising OK the last few days.

"I did pretty much everything I could to get myself ready here. I took a number of weeks off after Wimbledon.

"I obviously spoke to a lot of hip specialists. I tried resting, rehabbing, to try and get myself ready here."

Murray remained non-committal when asked when he might return, but said he would be making a decision in the next couple of days.

"I want to be back on court as soon as I can, that's what I love to do, I miss competing. I'll try and get myself back on court as soon as I can, but I need to make the correct decision and think it through with my team."

Murray underwent surgery to cure lower back problems in 2014, and such an option remains on the table.

Whatever course his recuperation takes, the Scot can draw inspiration from the way Nadal and Federer have come back from injuries this year.

Watch Murray's emotional press conference below.

The Spaniard missed last year's French due to a wrist injury, but won a record 10th title there earlier this year in June, and has now overtaken Murray at the top of the world rankings.

And the Swiss has enjoyed a second coming after missing the last five months of 2016 due to an injured knee, emerging victorious at both Melbourne and Wimbledon.