'Number One,' a new Eminem song produced by Dr. Dre, and allegedly intended for release on Em's much-anticipated album 'Relapse,' has leaked.

While the song starts off much as you'd expect, with a sung hook that works in typical whimsical Em style, the first and third verses are delivered in a much lower, simplified, Dre-esque flow, including lines that are clearly from Dre's perspective, prompting rumors that the song is actually an unfinished reference track recorded for Dre, so that he will know how to spit the verses Em wrote for him.

This is not the first time a reference track of Dre's has leaked. In May, a track allegedly planned for release on Dre's 'Detox' leaked, with reference vocals laid out by a rapper named Prophet, entitled 'It's Like That.' You can check that out here.