Coldplay/Rihanna Duet 'Princess Of China' Leaks Online

Chris Martin has called the hook-up the highlight of Mylo Xyloto.

Coldplay have performed more than half a dozen of the songs from their upcoming fifth studio album, Mylo Xyloto, in concert over the past year. But the one song that singer Chris Martin has called his favorite, a hookup with Rihanna called "Princess of China," has remained elusive.

That is until Monday morning (October 17) when the tune leaked online and the world finally got a taste of what the first guest vocal on a Coldplay album sounds like. The tune opens with typically epic, widescreen Coldplay fanfare overlaid with Rihanna wailing "Oh, oh whoa whoa oh," before settling down into a slinky, pulsing R&B beat. Martin is up first, whisper singing, "Once upon a time somebody ran/ Somebody ran away saying as fast as I can/ I got to go/ I got to go," before Rihanna comes in with the lines, "Once upon a time we weren't right/ All we ever seemed to do is fight/ On and on/ And on and on and on."

Ri goes on to dream about being a princess in a castle with her king and a ring, before lamenting, "You stole my star/ La la la la la la." The glitchy, spare keyboards come back in again before the "Whoa whoa oh" chorus explodes once more and the two singers entwine their voices for a chorus of " 'Cause you really hurt me" laments. Their vocals seem perfectly matched, with Martin's falsetto sitting nicely beside Rihanna's higher range. And like the thumping previously released "Paradise," the insistent beat on "Princess" is another nod to the more expansive sound on the upcoming album.

"Well, her bit on our record is my favorite bit ... when the song came out, it sort of asked for her to be on it," Martin said last month. "And I think at this point, we have nothing to lose, and so we've been trying some new things and trying to break down the perceived boundaries between different types of music. ... Because from where we're sitting, it seems like you can try and sound any way you like nowadays. You don't have to be in a rock box or a hip-hop box or a pop box, and I think it's fun when you embrace that idea."

The album is due out October 25, and the band will embark on a series of high-profile TV appearances to promote it, including a November 12 slot on "Saturday Night Live" with host Emma Stone. They'll also drop in at "The Colbert Report" on October 20, the "Today" show the next day and "The Ellen DeGeneres Show" on October 27.