P!nk's got the flu -- the nasty flu that's been spreading and intensifying this season -- and her illness could keep her from singing "The Star-Spangled Banner" on Super Bowl Sunday.
Sources close to Super Bowl LII production tell TMZ ... P!nk had a really tough time making it through her rehearsal Thursday night. We're told it didn't go smoothly ... and everyone involved didn't feel good when it was over.
There's more cause for concern too -- P!nk managed to power through her pre-Super Bowl concert Friday at The Armory in Minneapolis .