Led Zeppelin’s ‘Whole Lotta Love’ takes on the Who’s ‘I Can’t Explain' in a heavy-hitting round one Ultimate Classic Rock March Riff Madness battle.

It wasn't easy, but we managed to select 32 of classic rock's most iconic riffs, then paired them off into 16 first-round duels. Over the next five weeks the field will be repeatedly cut in half by your votes, until we theoretically arrive at the most awesome riff in all of rock history.

This challenge matches monster riffs by two ‘70s stadium-packing legends. With ‘Whole Lotta Love,’ and its distinctive staccato riff, Led Zeppelin not only took their still-germinating career to the next level on a global scale — they arguably invented ‘70s rock!

The Who dominated the ‘60s, alongside the Beatles and the Rolling Stones, and while the next decade would see them bringing the rock opera to the masses, it was simple but unforgettable riffs like the one in ‘I Can’t Explain’ that laid the foundation for their success.

So which of these stadium-packing behemoths will advance to the next round? You can vote once per hour until round one of March Riff Madness closes on Sunday, March 9 at 11:59PM ET. The final winner of Ultimate Classic Rock's March Riff Madness will be announced on April 7.

Watch Led Zeppelin Perform 'Whole Lotta Love'

Watch the Who Perform 'I Can't Explain'