James Hetfield and his bandmates return to headline Lollapalooza this year (15), and Farrell admits they'll have a much warmer welcome - because he has grown to like the band and its music.

He tells Rolling Stone, "I was very angry the first time they played Lollapalooza. I helped create the genre alternative, and alternative was against hair metal, teased-out hair, spandex, bulls**t rock music.

"Metallica, in my estimation at that time, wasn't my thing. I was into alternative and punk and underground... (I was) kind of harsh (on Metallica)... (It was) not the first group that I didn't want to play Lollapalooza, because I have an obligation to my patrons. I'm all about genuine, authentic, heartfelt, the real deal. So I was not sure about Metallica back in those days.

"(I felt) it's my f**king party and I'll have who I want."

But now Farrell admits, "I like their music."

Metallica will headline this year's (15) Lollapalooza in Chicago's Grant Park alongside Sir Paul MCCartney and Florence + The MAChine.

More than 100 acts will grace the festival's stages from 31 July (15) to 2 August (15).