Rock legend Bo Diddley and rootsy singer/guitarist Taj Mahal will fill out the list of guest opening acts on Tom Petty and the Heartbreakers' current seven-night stand at San Francisco's Fillmore Auditorium. Following in the footsteps of country rocker Lucinda Williams and Latin funk band War -- who will open Wednesday's (March 10) shows -- Taj Mahal will play Friday and Saturday while Diddley will open Monday and Tuesday. The pairing of Petty and Diddley makes sense given that the band played a cover of Diddley's "Diddy Wah Diddy" on the opening night of the Fillmore residency Sunday.