Trey Anastasio and Phil Lesh sat in with Colonel & The Mermaids at Terrapin Crossroads in San Rafael, CA last night. The pair joined the band—which, according to Deadheadland, featured Alex Koford, Grahame Lesh and Danny Eisenberg—in bar room for takes on the Grateful Dead staples “Bertha” and “Going Down The Road Feeling Bad.”

The surprise sit in marked Anastasio’s first collaboration with a member of the Grateful Dead since his performance with Furthur at the inaugural Lockn’ Festival in 2013. As previously reported, Anastasio will be teaming up with the core four surviving members of the band—Phil Lesh, Bob Weir, Bill Kreutzmann and Mickey Hart—as well as Bruce Hornsby and Jeff Chimenti for five Fare Thee Well shows this summer. The first of those concerts will take place at Levi’s Stadium in Santa Clara, CA on June 27 and 28, while the final three will take place at Chicago’s Soldier Field on July 3-5.