During a tour stop in Milwaukee on Tuesday night, the Rolling Stones hooked up with blues great Buddy Guy to cover Muddy Waters's "Champagne & Reefer."

Guy opened the show at the city's Summerfest, a stop on the Stones' ongoing Zip Code tour.

The band and Guy previously hooked up on the track for the Stones' 2008 concert film Shine a Light.

Speaking with Rolling Stone, fronter Mick Jagger says he's not sure what the group's plans are following the Zip Code trek.

"I'm looking at what the options are. We haven't etched it in stone."

He hinted that the band may be looking to record an album.

"Funny you should mention recording. Just last week, the word 'studio' popped up while we were rehearsing. I said, 'Well, let's find a time. I'm ready.'"

The Stones' next tour stop is in Kansas City.