The Australian Open is "most likely" to have a delay of one to two weeks from its mid-January state date, according to the sports minister of the state of Victoria.
"I think that's still the most likely," he told press, though adding it was "not the only option" for the tournament.
There also has been speculation around significantly longer delays, potentially a month or more.
The government of Victoria and Tennis Australia still have to finalize arrangements for players and teams to enter the country. There is currently a strict two-week quarantine, but Tennis Australia has asked permission for training or competition during those two weeks.
Otherwise, with the field already told they cannot enter till the beginning of January, there would be no gap between quarantine and the start of the Grand Slam events. Players have expressed concern about injury if they have to compete with little warmup.
Other schedule changes involve the Madrid Open. It announced it will extend its women's event by three days and bring forward the men's qualifying, making it a two-week event from April 27-May 9.
Tournament director Feliciano Lopez said organizers had sought the extension to a two-week event, which "will allow us to enjoy the best tennis in the world at the Caja Magica for a few more days" and offer more to its fans and sponsors.
The tournament was not played this season due to the coronavirus pandemic.
An announcement on the Australian Open is expected in a few days.