Bruno Mars' 'It Will Rain' has been tapped as the lead single from 'The Twilight Saga: Breaking Dawn - Part 1' soundtrack, a song that the singer-songwriter says was penned specifically for the highly anticipated film.

Although Mars was working on the song with the Smeezingtons before getting the 'Twilight' call, fans who are hoping that the song will be included on the 25-year-old's new album will be disappointed. "I personally think if I did this for the 'Twilight' soundtrack, then this is for the 'Twilight' soundtrack," he tells Billboard. "This is not for my album."

Twi-hards will be jealous to know that Mars has seen a majority of the latest installment of the 'Twilight' series, which he says is a "love story." He adds, "But it's a dark love story. And I think the best way to describe the song is: it's the darker side of love. I think that pretty much sums it up."

'It Will Rain' will premiere on the singer's website on Tuesday, Sept. 27., and fans can download the song exclusively on iTunes that day. As for his allegiance in the Team Edward/Team Jacob debate, Mars remains diplomatic. "I'm Team Bella all day," he admits.