During the 21st Century, both of these acts redefined the landscape of metal while achieving monumental success. Tapping into styles and concepts never quite tackled before, these bands capture the listener's imagination like few others. Which one of these discs will move on to the second round of our March Metal Madness tournament to determine the best metal album of the 21st century?

System of a Down made metal history with the release of 'Toxicity' in 2001. The album debuted at No. 1 on the Billboard Charts and has sold over 12 million copies worldwide. These unbelievable feats were accomplished by SOAD's four mad scientists, as the Armenian-American act injected Middle Eastern nuances into the album. With century-defining tracks such as 'Chop Suey!,' 'Toxicity' and 'Aerials,' the disc is arguably one of the most important albums of the 2000s.

With a more recent entrant, Swedish cult metallers Ghost (Ghost B.C.) had one of the best years of any metal band in 2013. Releasing their second studio album, 'Infestissumam,' the veiled Satanic cult converted fans all over the world, touring heavily with acts such as Iron Maiden and Slayer. Not only did 'Infestissumam' further the band's concept, the album delivered modern classics such as 'Year Zero,' 'Secular Haze' and the masterful 'Ghuleh/Zombie Queen.'

System of a Down's 'Toxicity' or Ghost's 'Infestissumam'? Vote for your favorite 21st Century album in the poll below!

(This poll will end on Sunday, March 9 at 11:59 PM ET. Fans are able to vote once per hour, so keep coming back to make sure your favorite album wins!)