Innuendo was released in early 1991 with an eponymous number 1 UK hit and other charting singles including, "The Show Must Go On". Mercury was increasingly ill and could barely walk when the band recorded "The Show Must Go On" in 1990. Because of this, May had concerns about whether he was physically capable of singing it. Recalling Mercury's successful performance May states; "he went in and killed it, completely lacerated that vocal". The rest of the band were ready to record when Mercury felt able to come in to the studio, for an hour or two at a time. May says of Mercury: “He just kept saying. 'Write me more. Write me stuff. I want to just sing this and do it and when I am gone you can finish it off.’ He had no fear, really.” The band's second greatest hits compilation, Greatest Hits II, followed in October 1991, which is the eighth best-selling album of all time in the UK and has sold 16 million copies worldwide.