It's not certain whether it'll appear on the long-awaited follow-up to 2008′s Death Magnetic, expected next year - but UK fans will be able to hear Metallica perform it during their appearance at Sonisphere in July.

Meanwhile, bassist Robert Trujillo has explained why he thinks the By Request sets have been dominated by material from the band's first five albums.

He tells Peru This Week: "There are some really good songs on those albums. Usually the fans of a band like the oldest songs the most.

"The energy and the spirit of the first five albums is special - and it helps us write music now that still has that flavour, without leaving behind what we are now."