According to drummer Lars Ulrich, there has been talk about Metallica touring with Green Day and U2.
"U2 came to San Francisco two summers ago, and we ended up having a lot to drink with them and Green Day following a dinner," Ulrich told MTV News. "I was told in the wee morning hours following this outing that members of U2, Green Day and Metallica agreed to tour together. We haven't talked about it since, but speaking for myself, I'd be very up for that."
Urlich has already declated himself "the hugest U2 fan."
"I would borderline call myself a [U2] groupie, actually," Ulrich said in a 2010 interview with Australia's Faster Louder. "Playing with U2 … I would fucking play on the parking lot. They're one of the only other bands that are still functioning after 30 years, just like we are, and I feel a lot of kinship in what they do and I just really admire and appreciate …
"They're really inspiring to me. I love their music, I love their way of reinventing themselves, and I love their way or thinking big and small. And it sort of works on all levels."