Martin described "Viva la Vida" as a new direction for Coldplay: a change from their past three albums, which they have referred to as a "trilogy". He said the album featured less falsetto as he allowed his voice's lower register to take precedence. Some songs, such as "Violet Hill", contain distorted guitar riffs and bluesy undertones. "Violet Hill" was confirmed as the first single, with a radio release date of 29 April 2008. After the first play, it was freely obtainable from Coldplay's website from 12:15 pm (GMT +0) for one week (achieving two million downloads), until it became commercially available to download on 6 May. "Violet Hill" entered the UK Top 10, US Top 40 (entering the Top 10 in the Hot Modern Rock Tracks chart) and charted well in the rest of the world. The title track, "Viva la Vida", was also released exclusively on iTunes. It became the band's first number one on the "Billboard" Hot 100, and their first UK number one, based on download sales alone.