Andy Murray says playing singles at the US Open looks "pretty unlikely" as he continues his return from hip surgery.

Murray, who won the title at Flushing Meadows in 2012, is through to the last 16 of the mixed doubles at Wimbledon with Serena Williams.

He won the men's doubles title at Queen's last month in his first tournament since undergoing a hip resurfacing procedure in January.

"There is a lot of stuff I need to get done physically," said Murray, 32.

The three-time Grand Slam champion added: "I think it's pretty unlikely just in terms of timing.

"The amount of work I need to do on the court to get ready for singles, the amount of work I need to put in off the court to get myself strong enough to play best of five sets, it's still quite a way away unfortunately.

"I would love to play. I need to look pretty long term with this. I don't want to be having to go through another big operation in a few years' time. I want to make sure the operation I've had lasts for as long as possible. To give it the best chance, I need to make sure that I'm physically really strong before I get back on the singles court."

Murray said it was not his intention to play smaller tournaments during the hard court season in the US, but was also unsure if he would travel Stateside to play doubles.

"Having felt how I felt these last few weeks, I'm positive about the future, so therefore I'm going to train properly to try and give singles a go," he said.

But he refused to put a timeframe on his return to singles, adding he may not be ready in time for the Australian Open in January.

"I know some people might like it to have taken five months or six months, but it's going to take more time than that, unfortunately," he said.

"Whether that's nine months or 12 months or 18 months, I don't know. I'll do my best to make it as soon as I can."