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Marcus Mumford and Justin Timberlake are joining forces. 

The pop superstar recently told Capital FM he and the Mumford and Sons frontman recorded a song together for the soundtrack to the Coen Brothers next film, Inside Llewyn Davis.  

Timberlake says he became good friends with Mumford during the process, even though it seemed like an odd partnership at first.  He says it's hard to imagine "any other world where [they] would have the opportunity to collaborate like that," but adds that it was "so much fun." 

Meanwhile, Justin also got a chance to get to know Marcus' wife, Oscar-nominee Carey Mulligan.  She and Timberlake both appear in the film, which is due out later this year. 

As for Mumford and Sons, frontman Marcus Mumford says there are "other sounds" he and his bandmates want to make on their third album.  He tells Rolling Stone that they'll always play the sound that permeates their debut Sigh No More and its Grammy-winning follow-up, Babel, but keyboardist Ben Lovett says they're ready to "make the departure" on their next studio effort.  And it could be quite a big departure. 

Mumford says with a smile on his face that they "really want to rap."  He explains that they have so much to say, and trying to match their words to a melody just isn't working anymore.  But Lovett suggests that the actual results of their musical exploration probably won't be that unfamiliar to fans.  He says that if Sigh No More and Babel are brothers, their third album will be a cousin. 

Even though Mumford and Sons are already kicking around ideas for the new album, it will probably be a while before it arrives in stores.  Banjo player Winston Marshall says the project "might take a few more years" to make than Babel, which was released three years after Sigh No More.