Assuming that there’s a seat available, it can be done. I have personal experience of doing it a couple of years ago.
The relevant rule is:
14.7.6 Subject to this clause 14.7, the following changes are permitted to a Classic Flight Reward flight before departure of that flight, provided the booking contains one or more Flight Segments that are not within Australia, and the Flight Segment(s) being changed do not include a partner airline that requires a ticket to be reissued for the change. Any such change will incur a Change Fee (see the
Fee Schedule) per passenger:
(a) change to flight number; and
(b) change to date of travel.