Juan Martin del Potro has withdrawn from the first tournament of the 2015 season due to a persistent wrist injury.
The Argentine was due to make his comeback at the Brisbane International following a lengthy layoff which has seen him miss the last 10 months of action.
Having retired during the first round of last February's ATP tour event in Dubai, the 2009 US Open champion underwent surgery to rectify the issue.
His comeback has now been delayed, however, with a return at the Apia International Sydney on January 12 instead being penciled in.
"I love playing in Sydney. The city and the fans are great and I can't wait to come back and defend my title," Del Potro told reporters. "Last year I played some of my best tennis there and it is the perfect way to start the year.
"I am looking forward to being back in Sydney as it is one of my favourite cities to play. I remember there were a lot of Argentine fans who came out to support me which was amazing."
Del Porto is currently ranked 137 in the world.
