Andy Murray has revealed that he expects to miss the remainder of the 2017 season due to a hip injury.
Murray ascended the ATP rankings after a stunning end to 2016 culminated with a Tour Finals victory over Novak Djokovic in London, but he has struggled ever since.
The Briton's sole title of the year came in Dubai in March and he failed to reach the final in any of the year's grand slams - his best run coming at the French Open where he lost to Stan Wawrinka in the semi-finals.
The hip complaint emerged during Murray's quarter-final defeat to Sam Querrey at Wimbledon and he has not played since, withdrawing from the US Open in August, with the issue apparently proving difficult to shake off.
Murray posted on Facebook: "Unfortunately, I won't be able to compete in the upcoming events in Beijing and Shanghai, and most likely, the final two events to finish the season in Vienna and Paris due to my hip injury which has been bothering me the last few months.
"Having consulted with a number of leading hip specialists over the last week, along with my own team, we have decided that this is the best decision for my long-term future.
"Although this has been a frustrating year on court for many reasons, I'm confident after this extended period of rest and rehabilitation that I will be able to reach my best level again and be competing for Grand Slam titles next season.
"I will be beginning my 2018 season in Brisbane in preparation for the Australian Open and I'm looking forward playing in Glasgow later this year against Roger [Federer] for UNICEF UK and Sunny-sid3up.
"I have a fantastic team working alongside me to help me through this process and appreciate the support from them and all of my fans over this difficult period."
Murray and his rival of last year Djokovic have each endured a miserable time of it in 2017, with the Serbian's season also ended early by injury.
In their stead, Rafael Nadal and Federer have shaken off fitness concerns of their own to bring a retro feel to major contention and the ATP rankings, which Nadal tops.
Nadal and Federer are on a collision course to meet in the US Open semi-finals, provided Federer can overcome Juan Martin del Potro.