Well, that was fast.

A mere day after the details for the stint were announced, Nicki Minaj has wielded the power of Twitter to announce she's is dropping out of the opening slot on Rihanna's Last Girl on Earth tour.

"Barbz I'm sorry 2 say I will not be going out on RiRi's tour. I've decided 2 use that time 4 the completion of my album. Hope u understand." Meanwhile, we are struggling to understand is what "barbz" means. And why this actually happened.

The singer and Lil Wayne protege has been the hot featured guest-of-the-minute so far in 2010, with her collabs with Ludacris, Young Money and others, her raunchy outfits and her latest vid for "Massive Attack."

No word on details about her forthcoming debut, although it seems like this tour would have been the pefect opportunity to increase awareness and hype for her tracks, since she's no household name yet. The Young Money collaborations has her playing with guys, but what about something for the ladies?

There's been no replacement announced yet, so it looks like Ke$ha's gonna have to enjoy the spotlight all on her own at the moment.

Pre-sale for the Rihanna tour went up today, the rest on April 9. Check here for complete dates and other details.