A previously delayed training session rescheduled for Monday evening was called off as concern mounts over the physical state of Novak Djokovic.

The nine-time champion at Melbourne Park has been wrestling with a right hamstring injury he picked up this month at the ATP Adelaide event.

The Serb tested the injury last Friday in an exhibition match at the Rod Laver area.

But Kyrgios himself withdrew from the Grand Slam a day before his Tuesday opening match due to a cyst on his knee.

The fear now is that Djokovic will join the Australian as a tournament no-show.

Djokovic is back a year after being deported for trying to enter Australia without a COVID vaccination – a jab he has sworn he will never take.