Smashing Pumpkins frontman Billy Corgan joined fellow ‘90s rockers Porno for Pyros at Lollapalooza for a rendition of Led Zeppelin’s “When the Levee Breaks.”

The surprise collaboration came towards the end of Porno for Pyros’ set. The group -- which replaced Perry Farrell’s better-known band, Jane’s Addiction, on the Lollapalooza lineup -- was nine songs into their performance when they welcomed Corgan to the stage.

“I love you all, Chicago,” Farrell declared to the crowd. “We have a very dear friend, Billy Corgan, that we got together [with]. Reunited this time out. We want to do a proper Chicago song for you together, is that cool?”

The musicians then powered through an emphatic rendition of “When the Levee Breaks,” with Farrell handling vocals while Corgan joined on guitar. The Delta blues track was originally written in 1929 and recorded by Kansas Joe McCoy and Memphis Minnie, but it was made famous in 1971 when Led Zeppelin released their version on Led Zeppelin IV.

Watch footage of the Lollapalooza performance below (Corgan's appearance begins at 37:38).

The festival collaboration capped a busy week for both artists. Corgan, a Chicago native, hosted a benefit concert on July 27 to support victims of the July 4 Highland Park mass shooting. During the event, the Smashing Pumpkins frontman premiered “Photograph,” a new song inspired by the tragedy. The singer explained that he’d found a picture of himself “standing in the very spot where this horrible thing happened,” leading him to view the image in a totally different way. “Good things become bad, bad things become good, simple things become complicated,” he noted, describing how the song came together.

Farrell also appeared at the benefit event, joining Corgan for a rendition of Jane’s Addiction’s 1988 hit “Jane Says.”

Smashing Pumpkins and Jane’s Addiction are scheduled to hit the road together in the fall for the Spirits on Fire tour.

Watch Porno for Pyros Perform at Lollapalooza 2022

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