Rock band Tool's Adelaide show has been postponed as fans were gathering at AEC Arena.
Fans were advised by Frontier Touring on Tuesday night that their tickets will be valid for Wednesday.
"Maynard James Keenan has been advised by doctors against performing this evening," Frontier said in a statement.
"Tonight's concert will be rescheduled to tomorrow night - Wednesday 1 May. All tickets remain valid and as allocated and do not need to be exchanged.
"If a patron is unable to attend tomorrow night, they are advised to seek a refund immediately from their original point of purchase."
Tool are due to play shows in Sydney, Brisbane and Auckland over the next few days.