London - Andy Murray on Tuesday ruled out playing singles at the US Open, indicating it could take up to 18 months before he felt ready to return.
The 32-year-old Scot had hinted that his successful hip surgery, as well as a promising foray into doubles at Wimbledon, could pave the way for a dramatic appearance at the season's concluding Grand Slam in August and September.
However, despite reaching the mixed doubles third round with Serena Williams, the former world number one said he would not return for singles in New York where he won his first Slam in 2012.
"I think it's pretty unlikely just in terms of timing. Just a lot of stuff I need to get done physically, to get myself stronger," said Murray whose ranking has slumped to 227 in the world.
"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 ways away unfortunately."
Murray's most recent singles match was at the Australian Open in January where he was defeated in five sets in the first round by Spain's Roberto Bautista Agut.
The three-time major winner even admitted in Melbourne that his career could be over such was the pain from his hip.
"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 added.
"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. I can't give an exact timeframe on this. It's tough."
On Tuesday, Murray and Williams made the third round of the mixed doubles at Wimbledon with a 7-5, 6-3 win over Fabrice Martin and Raquel Atawo.
They face top seeds Bruno Soares and Nicole Melichar for a place in the quarter-finals.
Murray also played men's doubles at Wimbledon with Pierre-Hugues Herbert with the duo reaching the second round.