New York - The family of Tom Petty on Wednesday released a previously unheard song by the late rocker as a preview of a box set full of new discoveries.
Keep A Little Soul - accompanied by a video created of archived concert footage and personal videos - is true to Petty's classic style, driven by a guitar that he plays at hard-rock volumes, but is rooted in the country and blues of the US South.
Petty's family said it uncovered the song from tapes of the sessions in which he recorded Long After Dark, his 1982 album notable for his rare flirtation with the synthesizers then being popularised by the New Wave movement.
The song will appear on An American Treasure, a four-CD set coming out on 28 September that features dozens of entirely new tracks or alternate and live versions of Petty's songs.
His daughter, Adria Petty, and widow, Dana Petty, said that the box set spanned all 40 years of his career and that they expected more new music in the future.
Petty "accumulated a wealth of unreleased music in his vaults, and we have collectively uncovered one gem after another that will keep us all listening and discovering new facets of Tom's talent for many years to come," they said in a statement.
The box set was apparently designed with serious fans in mind and includes few of Petty's best-known hits. It features a live version of "I Won't Back Down" but not Free Fallin', Runnin' Down a Dream, Learning to Fly or Don't Come Around Here No More.
Petty, a 66-year-old Florida native whose catchy melodies belied his dark storytelling, died from an accidental overdose of drugs including opioid painkillers.
Petty, who had just completed a tour celebrating four decades with his band The Heartbreakers, had been suffering pain from a fractured hip.
His death came amid an epidemic in the United States of painkiller addiction.