And he believes Japan's latest export Babymetal - fronted by three schoolgirls performing a mix of pop and metal - deserve credit for their work.

Friedman tells Rolling Stone: "Babymetal, if you strip off that heavy metal guitar stuff, all you have is your basic fun, quirky, Japanese pop stuff. But the interpretation is super-metal.

"To me, it sounds like Meshuggah with Japanese pop on top of it. So for someone like me who's been playing metal forever, it's really fresh to hear. I mean, I can hear another Pantera song, and it's great, but we've heard it before a billion times."