Aerosmith's 'Walk This Way' takes on Lynyrd Skynyrd's 'Sweet Home Alabama' in the quarterfinals of March Riff Madness. The winner will represent the U.S.A. bracket in the semifinals.

Two weeks ago, we started with 32 of rock's most iconic riffs. Now, that field has been whittled down to eight. We'll keep going until we theoretically arrive at the most awesome riff in all of rock history.

'Sweet Home Alabama,' which commands you to "turn it up" when it comes on the radio, got to the quarterfinals by beating Ted Nugent's 'Stranglehold' in round one and ZZ Top's 'La Grange' in round two. 'Walk This Way,' for its part, dispatched of 'Mississippi Queen' by Mountain, then 'Rocky Mountain Way' by Joe Walsh in the second round.

So which is the U.S.A. bracket's best riff? You can vote once per hour until the quarterfinals of March Riff Madness closes on Sunday, March 23 at 11:59PM ET. The ultimate March Riff Madness winner will be revealed on Tuesday, April 7.

Watch Lynyrd Skynyrd Perform ‘Sweet Home Alabama’

Watch Aerosmith Perform ‘Walk This Way’

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