The Australian Open will start on 8 February next year after being pushed back three weeks because of the coronavirus pandemic.
The first Grand Slam of the 2021 season was scheduled to take place in Melbourne from 18-31 January.
The four-day qualifying event has been moved to Doha, Qatar and will start on 10 January.
Players will arrive in Melbourne on 15 January for a 14-day quarantine period under local coronavirus rules.
The news was confirmed when the ATP announced the schedule for the first seven weeks of the men’s tour next year.
The season will start with events in Delray Beach in the United States and Antalya in Turkey on 5 January.
There will be two tournaments in Melbourne starting on 31 January – one of which is the relocated Adelaide International – while a condensed 12-team ATP Cup will take place from 1-5 February.
“The reconfigured calendar for the start of the 2021 season represents a huge collaborative effort across tennis, under challenging circumstances,” said ATP chairman Andrea Gaudenzi.
“Health and safety will continue to be paramount as we navigate the challenges ahead.”