As an aficionado and purveyor of all things relating to nostalgia and the blues, it is unsurprising that Jack White is a fan of Led Zeppelin. And with former Zeppelin frontman Robert Plant‘s revelation last year that he would like to record with White, it seems that the admiration is mutual. Accordingly, as both Plant and White were on the bill at the Lollapalooza Argentina festival, an onstage collaboration seemed likely, if not inevitable.

Sure enough, shortly after White and his band broke into the opening riff from Led Zeppelin II classic “The Lemon Song,” Plant joined them onstage to a roar of recognition from the crowd and showed that he can still belt out a song that has long been out of his usual repertoire (although, not out of White’s).

Both Plant, clad in a leather jacket over a white t-shirt, and White, dressed in his usual vampire/greaser getup, seemed to be enjoying themselves during the collaboration, with Plant grinning while White tore off a scorching, staccato solo and even the famously dour White cracking a smile or two. As the song ended, the two men shared a brief embrace, and Plant walked offstage as White told the crowd, “You know who that was; I don’t have to tell you.”

Watch Robert Plant join Jack White and his band for “The Lemon Song” below: