Coldplay's seventh album, A Head Full Of Dreams, drops on Dec. 4, and so far, we've only heard a little bit of what it actually sounds like. Lead single "Adventure Of A Lifetime" is disco-y, while the two new tracks that popped up over the weekend -- "Up&Up" and the title track -- were as big and stadium-friendly as we'd expect.

But there's an even larger detail we're still waiting to find out about -- what exactly is President Obama doing on the title track to A Head Full Of Dreams?

Band leader Chris Martin told The Sun over the weekend that Coldplay snagged a snippet of Obama singing "Amazing Grace" at slain Charleston pastor Rev. Clementa Pinckney's funeral in June.

"We have a tiny clip of the President singing 'Amazing Grace' at that church. Because of the historical significance of what he did and also that that song being about, ‘I’m lost but now I’m found,'" Martin said. A source with ties to the band reportedly said that Obama wouldn't greenlight the use of his vocals for "just anyone," but as a fan of the band, Obama gave his approval.

Obama joins the mom-and-daughter duo of Beyoncé and Blue Ivy Carter as well as Tove Lo, Oasis' Noel Gallagher and, oddly, Martin's ex-wife Gwyneth Paltrow on the long list previously announced guest performers for A Head Full Of Dreams.

Now if we can only get Bill Clinton on Views From The 6...