Six-time champion Roger Federer will miss the Australian Open for the first time in his career as he continues his recovery from knee surgery.
The 39-year-old Swiss, a 20-time Grand Slam winner, has not played since January because of two operations.
He hoped to return at the delayed Australian Open, which starts on 8 February in Melbourne.
"Roger ran out of time to get himself ready for the rigours of a Grand Slam," said tournament director Craig Tiley.
Federer has played in the Australian Open 21 years in a row, but his agent said missing the tournament was "the best decision for him in the long run".
Federer's most recent last competitive match was a semi-final defeat by eventual champion Novak Djokovic in this year's Australian Open.
In February, Federer had arthroscopic surgery on his right knee.
He hoped to return in July, but in June he had another operation that ruled him out for the rest of 2020.
This month Federer said he faced a "tight" race to be fit for the Australian Open, despite the tournament being pushed back three weeks because of the coronavirus pandemic.
Tennis correspondent Russell Fuller
Federer has been training in Dubai but, even with a three-week delay to the Australian Open, will not be ready in time.
Very few will be looking forward to the two weeks' quarantine in Australia, during which players must stay in their rooms for 19 hours a day.
But it must be even more unappealing for older players with families - and especially for those still striving for full fitness.
Federer's agent Tony Godsick says he will "start discussions this coming week for tournaments that begin in late February".
There is not yet an official schedule, but playing an indoor event in Europe before heading to Dubai, where Federer is an eight-time champion, would seem an ideal way to resume.
He has played sparingly on the clay in recent years, with Wimbledon and the US Open likely to be his main goals for 2021.