It all started when Meek Mill, a Philadelphia-born rapper, claimed on Twitter that Toronto's Drake doesn't write his own rap music.
Drake has yet to respond.
But Kelly, who frequently Tweets at Drake and references him on social media, issued the following salvo: "You're no longer welcome in Toronto, @MeekMill."
The Tweet made headlines in rap music magazines and around the world. In the hours after the Tweet, Kelly was trending on Twitter.
The Tweet barring Meek Mill from Toronto has been shared more than 40,000 times.
Meek Mill, coincidentally, will be in town touring with Nicki Minaj next week.