The Australian Open will start on February 8, three weeks later than scheduled, the ATP Tour said in releasing an update of its calendar for 2021 revising the first seven weeks of the season.
The start date of the main draw of the year's first Grand Slam was originally slated for January 18 and organisers Tennis Australia have been in drawn-out negotiations with local government over COVID-19 health measures.
Tennis Australia was not immediately available for comment.
The ATP release said men's qualifying for the Australian Open would take place in Doha from January 10-13 before players relocated to Melbourne to enter quarantine.
The ATP tournament scheduled to take place in Adelaide has been moved to Melbourne to be played in the week commencing January 31, alongside another men's tournament in the city.
A shortened version of the ATP Cup men's team tournament will take place in Melbourne from February 1-5 before the Grand Slam begins on the following Monday.
The ATP season will open with tournaments in Delray Beach, Florida and Antalya in Turkey before preparations for Melbourne Park begin.
Australia were dealt an early blow in their quest to reach the Super Eight stage of the Twenty20 World Cup after the depleted former champions crashed to a 23-run defeat by Zimbabwe in Colombo on Friday.
Arsenal has wasted the chance to restore their six-point lead at the top of the Premier League table as they were held to a 1-1 draw at Brentford on Thursday, with Noni Madueke's second-half header cancelled out by Keane Lewis-Potter.
Defending champions India continued their march towards the Super Eight stage of the Twenty20 World Cup with a 93-run win over Namibia in a group A contest at Arun Jaitley Stadium on Thursday.
Brothers Justin and Anthony Mosca guided Twenty20 World Cup debutants Italy to their first win in the tournament, as their unbeaten half-centuries secured a dominant 10-wicket victory over Nepal in a Group C clash on Thursday.