Andy, Kei pull out

Former world number one Andy Murray and Japan's Kei Nishikori pulled out of the Australian Open Thursday as a host of top names battle to be fit for the year's first Grand Slam.

Murray had failed to recover from a hip injury sustained last year and has not played since losing in the Wimbledon quarterfinals last July, while Nishikori has been on the sidelines since August due to a torn tendon in his right wrist.

"Sadly I won't be playing in Melbourne this year, as I am not yet ready to compete," the three-time Grand Slam champion 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."

Murray, who earlier withdrew from the Brisbane International, did fly from Queensland to Melbourne, but only to catch a connecting flight back to Europe, ABC reported.

Australian Open tournament director Craig Tiley said he respected what was a "very hard decision for Andy."

The loss of the Scot, who may now opt for surgery on his hip, came with injury clouds hanging over a who's who of stars before the Open begins on January 15

World number one Rafael Nadal and six-time Australian Open champion Novak Djokovic remain huge doubts having yet to play a competitive match this year.

World number eight Jack Sock joined the growing injury list when he injured his hip at the Hopman Cup in Perth on Tuesday. Former champion Stan Wawrinka and Canada's Milos Raonic are also returning from injuries but intend to play in Melbourne.

Asian number one Nishikori said his rehab had been "going well but I am just not ready 100 percent to come back yet in best of five set matches".