What happens when a vacationing rock legend crosses paths with a band headlining a major music festival? Lisbon, Portugal’s Rock in Rio festival found out Thursday night as the Rolling Stones brought out a special guest during their headlining performance: Bruce Springsteen, who joined the band for “Tumbling Dice.” Springsteen arrived, guitar in hand, to trade verses with Mick Jagger on this searing rendition of the Exile on Main St. classic. Watch fan-shot footage of Springsteen’s surprise appearance above.

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Earlier in the day, Springsteen’s wife Patti Scialfa hinted on Instagram that a collaboration might be in the works by acknowledging that the Springsteen family were in Lisbon and posting a #ThrowbackThursday photo of her, Bruce, and Jagger.

The Lisbon concert was only the Rolling Stones‘ second show since postponing their Australian tour following the death of fashion designer and Jagger’s girlfriend L’Wren Scott. Ironically, the Stones’ previous concert last week in Oslo, Norway was attended by the E Street Band guitarist Steven Van Zandt, who films his Netflix series Lilyhammer in Norway. The Stones’ 14 on Fire Tour next visits Zurich, Switzerland on June 1st, so maybe be on the lookout for Nils Lofgren.

Bruce Springsteen & The Rolling Stones perform 'Tumbling Dice'
This isn’t the first time the Stones and Bruce have performed together: In December 2012, when the Rolling Stones visited Springsteen’s home turf with a gig at Newark, New Jersey’s Prudential Center, Springsteen also joined the band for a rendition of “Tumbling Dice.” That concert, which also featured guest appearances by Lady Gaga, the Black Keys, and former Stones guitarist Mick Taylor, was broadcast on pay-per-view.

Even when Springsteen isn’t joining Mick Jagger for a stroll down the catwalk, his E Street gigs occasionally feature some Stones covers: “The Last Time,” “(I Can’t Get No) Satisfaction,” and “Jumpin’ Jack Flash” have popped up in Bruce’s setlists, and during a 1984/85 tour, the E Street Band covered “Street Fighting Man” on a nightly basis. Springsteen also joined Alejandro Escovedo for “Beast of Burden” at New Jersey’s Stone Pony in 2010.