Get ready for the pop music world to implode!

I can exclusively reveal that Miley Cyrus' surprise guest performer for her upcoming MTV Unplugged special is none other than Madonna!

Yes, Miley and Madonna singing together!

Sources tell me that the two were on a Hollywood soundstage earlier today rehearsing the collaboration.

No word on what exactly they'll be performing, but does it really matter? They could read the telephone book together and the world would watch and listen.

Miley Cyrus: MTV Unplugged tapes tomorrow (I'll be there!) and will air on the music network Wednesday night at 9 p.m.

"The performance will showcase a more intimate side of Cyrus and feature surprise guests for an unexpected re-invention of the songs that have defined her career, including several from her #1 critically acclaimed album, Bangerz," MTV said in a press release last week. "Miley and her fans have always had an intimate and direct connection through her music, personality and no-holds-barred attitude and the Unplugged stage will serve as the perfect platform for her to show viewers what inspires and ignites her music and her passions."

Since its debut in 1989, Unplugged has showcased Nirvana, Bruce Springsteen, Katy Perry, Mariah Carey, Adele and Florence + The Machine.

E! Online