Phish will kick off their three-night run at Colorado’s Dick’s Sporting Goods Park tonight, and bassist Mike Gordon arrived a day early last night, sitting in with Dumpstaphunk, who were playing Denver’s Cervantes’ Masterpiece.

As JamBase reports, Gordon came onstage to help out with a cover of Son Seals’ “Funky Bitch,” taking on lead vocals before trading his bass for a guitar during the ending jam, closing it out with a solo. The tune has been covered by Phish and Gordon’s solo band but was a debut for the New Orleans funk outfit last night. Gordon also reportedly sat in for a run of DNCE’s “Cake by the Ocean,” a song that was also covered by The String Cheese Incident earlier this year at Electric Forest.

Watch a video of the performance above, courtesy of YouTube user Long J. Phish’s three-night stand at Dick’s starts tonight, while Dumpstaphunk will head to California for a stop at Sweetwater Music Hall in Mill Valley tonight.