Andy Murray says he is "gutted" to miss the Australian Open after failing to recover in time from an injury picked up at the Davis Cup finals last month.
The 32-year-old's contribution to Britain's efforts in Madrid was restricted to one match after he suffered a problem with his pelvis.
It was initially thought the issue was minor and would not affect his participation in either the season-opening ATP Cup or the Australian Open, which was set to be Murray's grand slam comeback.
But alarm bells rang when he cancelled his training block in Miami and on Saturday his management company announced the Scot would not be travelling to Australia.
"I've worked so hard to get myself into a situation where I can play at the top level and I'm gutted I'm not going to be able to play in Australia in January," Murray said.
"After the AO this year, when I wasn't sure whether I'd be able to play again, I was excited about coming back to Australia and giving my best, and that makes this even more disappointing for me.
"Unfortunately I've had a setback recently and as a precaution, need to work through that before I get back on court competing."
Tennis Australia CEO Craig Tiley added, "I know how excited Andy was about coming back to compete in Australia in January, and how disappointed he is not to make it for 2020.
"Andy's last match at the Australian Open was a five-set rollercoaster that none of us who witnessed it will ever forget. His determination and iron will was on display for all to see, and it's that fighting spirit that has driven him to come back from a potentially career-ending injury to achieve the results he has this year.
"Although we will miss him in January, we wish him all the very best for his recovery and look forward to seeing him back on court very soon."
Murray is now back on court but, given it is still relatively early days in his comeback from hip surgery in January, his team made the decision not to rush his return to competitive tennis.