She would be worried about KE$HA not Nicki Minaj...because Ke$ha is probably equally if not more popular than Rihanna right now.

False. Nicki needs to be worrying about her ALBUM with a first already slowing down @ 3 Mill, that's why she got off.
Just like when Ciara asked out of Britney's tour to work on her new album.

...goes to find out who Ke$ha is...

Media Take out = Automatic Credibility fail

I only wanted to see the tour because of Nicki.

DEAD. This is pure BS, why would Rihanna be scared of Nicki, rather than Ke$ha?

LOL. Where is Massive Attack on the charts? Oh Okay.

MTO = SIT.