Singer-songwriters Madi Diaz and Lucy Dacus have released a new duet version of Diaz's song "Heavy Metal", following a weekend of collaborative performances together at the Newport Folk Festival. The pair had already appeared together on stage during the festival, including guesting on Hayley Williams' set, before Diaz shared the studio recording of their reworked track.

The original "Heavy Metal" featured on Diaz's 2025 album Fatal Optimist, and the new duet version will appear on an expanded "UN-unplugged" deluxe edition of the record, due for release on 4 September via Anti- Records. Diaz has praised Dacus's contribution, comparing her vocal to Frank Sinatra and saying she was "honoured" to have her feature on the song, which was also performed live during Dacus's Newport set.