The duo has been performing cover songs during their European tour
Robert Trujillo and Kirk Hammett , bassist and guitarist of Metallica , have been playing unusual covers at each of the band's shows across Europe. In Switzerland they played "Procreation Of The Wicked" by Celtic Frost , in Norway it was "Take On Me" by A-ha , and in Sweden it was "Dancing Queen" by ABBA .
ABBA is one of the best-known groups in Sweden, where there is a museum dedicated to the band, and they were also the subject of a film, "Mamma Mia!".
