Rob Zombie and Black Sabbath are no strangers, having toured together on Ozzfest, but they'll have to go from friends to foes in March Metal Madness as "Feel So Numb" and "God Is Dead?" duke it out on the road to being crowned the Best Metal Song of the 21st Century.

Rob Zombie's "Feel So Numb" overcame Killswitch Engage's "My Last Serenade" to take the lead in an overnight victory. It's proof anything can happen in this tournament and Zombie will need all the votes possible taking on the mighty Black Sabbath.

Black Sabbath's "God Is Dead?" had an interesting opponent in Round 1, taking on progressive metal luminaries Opeth and their song, "The Grand Conjuration." With over two thirds of the votes, it was smooth sailingfor Sabbath, and the band will be looking to keep the ship righted against Rob Zombie in Round 2.

So which song will move on to the Quarterfinals of March Metal Madness 2016? Listen to both tracks and vote for either Rob Zombie's "Feel So Numb" or Black Sabbath's "God Is Dead?" as the Best Metal Song of the 21st Century in the poll below!

(This poll will end on Tuesday, March 15, at 9AM ET. Fans are able to vote once per hour, so keep coming back to make sure your favorite song wins!)

Rob Zombie, "Feel So Numb"

Black Sabbath, "God Is Dead?"