Singer Pink has postponed Friday night's show at the Bell Center.
She says in a Twitter message it's a flu virus she's been battling for a while, adding she normally gets through it.
The Grammy Award-winning performer said she was "gutted" to make the announcement.
"Our entire family has been battling this awful virus/flu for two weeks now, and I have battled my way through these shows because postponing sucks,” the message says.
She goes on to say "I’m really sorry and know that I have done everything I could to avoid this."
No new date for a Montreal show had been announced.