Within weeks of "Fireball"s release, the band were already performing songs planned for the next album. One song (which later became "Highway Star") was performed at the first show of the "Fireball" tour, having been written on the bus to a show in Portsmouth, in answer to a journalist's question: "How do you go about writing songs?" On 24 October 1971 during the US leg of the Fireball tour, the band was set to play the Auditorium Theatre in Chicago when Ian Gillan contracted hepatitis, forcing the band to play without him, with bassist Glover singing the set. After this, the rest of the US dates were canceled and the band flew home.