Ozzy Osbourne's 'Crazy Train' takes on Iron Maiden's 'Two Minutes to Midnight' in round two of Ultimate Classic Rock's March Riff Madness.

Last week, we cut down the initial field of 32 of rock’s most iconic riffs down to 16. And this week we’ll halve it again, then repeat the process for the rest of the month until we theoretically arrive at the most awesome riff in all of rock history.

Performed by the late, great Randy Rhoads, 'Crazy Train' easily dispatched the Scorpions' 'Rock You Like a Hurricane' in round one. Iron Maiden's 'Two Minutes to Midnight,' on the other hand, won a close battle against Def Leppard's 'Photograph.'

So which one moves forward? It's entirely up to you. Everyone can vote once per hour until round two of March Riff Madness closes on Sunday, March 16 at 11:59PM ET. The ultimate March Riff Madness winner will be revealed on Tuesday, April 7.

Watch Ozzy Osbourne & Randy Rhoads Perform 'Crazy Train'

Watch Iron Maiden Perform 'Two Minutes to Midnight'