The Moulin Rouge! star was scheduled to pick up the Companion in the Order of Australia award in Canberra during Australia Day, but cancelled her appearance.
A government official says, "We almost had Keith Urban to come and perform - it was so close. It we had Keith, we would've had Nicole, too."
Organisers had to scramble to find a last minute replacement and were able to convince Russell Crowe to perform in place of the country crooner.