Sum 41 frontman Deryck Whibley looked back at his performance alongside Rob Halford and Tommy Lee, calling it the “single most important moment” in his band’s career.

The gig took place in August 2001 during a special televised event celebrating MTV’s 20th birthday. In a recent interview on the Tuna On Toast With Stryker podcast, Whibley recalled how it all came together.

“That was the single most important moment in our career and in our lives at that time,” Whibley admitted. “Because we were a relatively still unknown band, the song [‘Fat Lip’] was starting to go, but it wasn’t a hit or anything yet, and we were lucky enough to get to be able to play that show and we were the opening of the whole night. So we were such fans of what we’d seen on MTV Awards and things of these collaborations of artists. So when we got our first opportunity to do something on MTV, we asked them, ‘Can we do a medley and ask some other artists to come out?’ And they were, like, ‘Great!’’

With MTV’s blessing, Sum 41 put together a wish list of collaborators.

“We said Tommy [Lee], we said Rob Halford, we said the Beastie Boys and we asked for Slash,” Whibley revealed. “Slash said no, Beastie Boys said no, but Tommy and Rob said yes. So then all of a sudden we were like, ‘They said yes? So now we gotta do this thing?’ I mean, we just kind of threw that out there. We didn’t think it was actually gonna happen.”

Watch Dereck Whibley Discuss Sum 41's Performance With Tommy Lee and Rob Halford

The members of Sum 41 got to work putting together a medley of tunes. They’d start with their song “Fat Lip” before rolling into Beastie Boys’ “No Sleep Till Brooklyn,” Motley Crue’s “Shout at the Devil” and Judas Priest’s “You’ve Got Another Thing Comin’.”

“We didn’t really have much time to get it together,” Whibley revealed. “We had one rehearsal the night before. So Tommy flew in and Rob came in and we worked on this thing. We ran it a few times. We left the rehearsal thinking, ‘I think we have it. I mean, we’ll see.’”

Whibley admitted he and his bandmates were “shaking backstage” moments before the show started. “I don’t think I’d ever been as nervous in my life yet.”

Then, Sum 41 proceeded to step into the spotlight, triumphantly rocking through the medley with two of their idols joining them. Lee was rolled onto the stage on a riser during “No Sleep Till Brooklyn” and remained to pound away for the remainder of the performance. Halford, meanwhile, appeared for “You’ve Got Another Thing Comin’,” much to the delight of the crowd.

The performance, which you can watch below, proved life-changing for Sum 41.

“It just felt like the rest of the night everyone was congratulating us. Everyone was saying, you have no idea, this is so big for you guys,” Whibley recalled. “And from the next day, everything sorta took off. The [‘Fat Lip’] video went into heavy rotation, the song went up the charts, and it just kinda went worldwide, and it just kinda took off.”

Judas Priest Albums Ranked

They don't call 'em Metal Gods for nothing.