World No 22 Kei Nishikori has announced his decision to withdraw from this month's Australian Open to continue his rehabilitation following long-term injury.
The Japanese player suffered a wrist problem last summer, which included a torn tendon, ruling him out of the second half of 2017.
Nishikori, 28, was hoping to be back in time for the first grand slam of the year, which starts on January 15, but has decided he is not yet prepared for the rigours of five-set matches.
"I am very sorry to announce that I will miss the Aussie Open this year," he posted on his app, keisapp.com.
"The Aussie Open is my favourite Slam...it's my "home" Slam...it's the Slam that takes incredible care of the players and their teams....and it hurts that I will have to miss it this year.
"My rehab is going well but I am just not ready 100 per cent to come back yet in best of five set matches."
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Nishikori, a three-time quarter finalist in Melbourne, last played a competitive match in August.
He is the first man to confirm his withdrawal from this year's tournament, with doubts remaining about a host of other big names.
Former world No 1 Andy Murray continues to struggle with a long-term hip problem, while 12-time grand slam winner Novak Djokovic has an elbow issue, world No 1 Rafael Nadal has a knee injury and 2014 Australian Open champion Stan Wawrinka is also battling to regain full fitness.
According to his agent Olivier van Lindonk, Nishikori will make his comeback as a wild card at the Newport Beach Challenger competition later in January before playing tournaments in Dallas, New York and Mexico.
In a statement, Van Lindok said: "Kei's progress is going really well.
"He is continuing to improve every week [as the medical team predicted] and we are happy with the progress.
"Last week was the best week so far and he practised twice a day, four days in a row.
"The team carefully evaluated Kei coming back in Melbourne.
"However, coming back in a best of five-set match situation just doesn't seem to make sense at this stage in his comeback."