The Rolling Stones played the first festival date of their 2015 Zip Code tour at Milwaukee's Summerfest last night, and managed to work in a performance of "Champagne and Reefer" with their old friend — and show opener — Buddy Guy.

The Stones have a long history with the legendary guitarist, dating back to the early '70s, when Guy and Junior Wells were tabbed as their opening act on a tour of Europe. At the time, Guy was suffering a sales slump even as his earlier records were being touted as influences over an emerging class of young guitarists that included Keith Richards and Eric Clapton, and he later attributed his subsequent commercial revival in part to the leg up he received from the Stones.

"When you open a show for them, some fans are gonna look up and say, 'That’s not the Rolling Stones!' Sometimes the few people there who knew us — two or three maybe — were okay," Guy told Guitar World in 2014. "But the rest of the 40, 50 or 60 thousand were saying, 'Who the hell is this?' A lot of people weren’t ready for me and Junior back then. But I kept saying to myself, 'Well, they got us out here. Play a few licks and maybe you’ll sell a few more records next time you make one because somebody saw you with the Rolling Stones.' But it was exciting. And even today I get people right now coming up and saying, 'I didn’t know who you was till I saw you on a stage with the Stones.'"

Guy's appearance, which you can watch via the fan-shot footage above, was one of the more memorable moments from a 130-minute set that the Milwaukee Journal Sentinel said "lived up to the band's legendary legacy." And it was certainly a personal highlight for Stones singer Mick Jagger, who recorded a backstage message with Guy.

The Stones now move on to Kansas City, where they're scheduled to perform on June 27 with special guest Ed Sheeran.

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