Metallica and Lady Gaga were paired up for a performance of the former’s “Moth Into Flame” at the Grammys Sunday, but were plagued with audio issues.

METALLICA & LADY GAGA PERFORM “MOTH INTO FLAME”

At first, Metallica lead singer James Hetfield‘s microphone wasn’t working, and eventually he ventured over to share a mic with Gaga. Behind them was a crazy pyrotechnic showing, and the crowd was loving it.

At one point, Gaga got into the spirit and jumped in to crowdsurf. At the end, Hetfield was visibly angry at the mic problems and threw his mic to the ground, while throwing his guitar off stage.

While many were confused about the pairing, Gaga was on board. “I was at Bradley [Cooper’s] house with Lars [Ulrich] and we were just hanging out,” she explained. “He’s amazing. I went to see them live. I saw them recently and we were watching the show; those guys play better than they’ve played in their whole lives.”

Metallica was up for one Grammy this year for Best Rock Song for “Hardwired,” but lost to David Bowie’s “Blackstar.” Their latest album, Hardwired … to Self-Destruct, was released in November, just missing the Grammy deadline.

Gaga topped off one of the biggest weeks in her career after headlining the Super Bowl Halftime Show last Sunday. She also announced a world tour for her latest album Joanne, which after the Super Bowl, jumped from No. 66 to No. 2 on the Billboard 200 chart.