Tom Petty & the Heartbreakers are in town for two shows at TD Garden – they play Thursday and again Friday - but the band had Wednesday to itself. Some members no doubt just hung around the hotel catching up on “Game of Thrones” or old episodes of “Veep.”

But guitarist Mike Campbell ventured out on the town, ending up at the Somerville club Thunder Road, where he joined local Grateful Dead tribute band Bearly Dead. Campbell fit right in, adding a few choice licks to covers of the Dead songs, “Loser” and “The Other One.”

Benny Tucker, who manages Bearly Dead, said someone in the band recognized Campbell having a drink at the bar, so Tucker said he walked over and said hello.