Metallica are one of the last bands you'd expect to see on an American Idol finalist's playlist. However, it would seem that Adam Lambert is a closet Metallica fan.
On October 17th in Auckland, New Zealand, Adam and his band ended their set with a surprise cover of the Bay Area Thrashers' 1991 anthem Enter Sandman.
Speaking to Australian radio station Triple M, Lambert revealed his reasons for including the cover: "It's one of [guitarist] Tommy's favourite songs. We practiced it that afternoon for the first time and we kind of threw it up there. It was a lot of fun.
Lambert is no stranger to singing classic rock music. He performed Led Zeppelin's Whole Lotta Love during the American Idol competition and performed a medley with glam rock juggernauts Kiss on the show's semi-final.
Despite past dabbling, a Metallica cover is probably the heaviest thing Lambert has ever done.
Metallica have yet to comment on the performance, but Lambert has already defended himself against a potential onslaught from the band's fans: "I think any song could be covered if a musician wants to cover it. I don't really think any song is sacred. There are great songs, there are beautiful songs and I think anybody has the right to sing them."
A video of Lambert's performance is available below: