Sydney - Former world number one Andy Murray withdrew from the Australian Open Thursday after failing to recover from a hip injury, joining injured Japanese star Kei Nishikori on the sidelines.
The 30-year-old suffered the injury last year and has not played on the ATP tour since losing in the quarter-finals at Wimbledon.
"Sadly I won't be playing in Melbourne this year, as I am not yet ready to compete," Murray said in a statement.
"I'll be flying home shortly to assess all the options but I appreciate all the messages of support and I hope to be back playing soon."
Australian Open's tournament director Craig Tiley said he respected what was a "very hard decision for Andy".
"We are fully aware that Andy has been going through a difficult period with his hip and that he's done everything possible to prepare for the Australian summer," Tiley added.
Murray's withdrawal comes amid a string of injury concerns that have plagued some of the world's top players and cast doubt on their participation first Grand Slam of the year, which is due to begin in Melbourne on January 15.
Asian number one Nishikori, who has not played competitively since last August after suffering a torn tendon in his right wrist during a practice session at Cincinnati, also pulled out of the Slam earlier on Thursday.
Former world number one and six times Australian Open champion Novak Djokovic has not played since a right elbow issue forced him to quit Wimbledon in the quarter-finals in July and has already cancelled scheduled appearances at an exhibition in Abu Dhabi and the Qatar Open in Doha.
He said he intended to test the injury next week at two exhibition events in Melbourne next week, the Kooyong Classic and Tie Break Tens.