James Hetfield handled Metallica's tech issue like a seasoned vet during the band's joint performance with Lady Gaga at the Grammys last night (Feb. 12). With his microphone turned off, the frontman was forced to share a mic with Gaga, which added a genuine sense of rock 'n' roll flair. Now, TMZ reportedly has discovered who is to blame for this mishap.

The news outlet states, "Sources connected to the production tell us everything was fine right before the 'Moth Into Flame' [collaboration] was about to begin," noting that the line check "went off without a hitch" prior to the televised live performance. Furthermore, TMZ detailed that between the run-through and the live set, a wire under the stage accidentally became unplugged by a stagehand, but the Grammys had not responded to comment at press time.

The problem managed to get fixed right before the end of the song, which ended with Hetfield kicking his mic stand and lackadaisically tossing his guitar to a crew member. Metallica's post-Grammy performance was a different story, however, as the thrash icons played a scorching set to a small 3,000 person crowd immediately after the conclusion of the awards show.

Metallica did not comment on the snafu until late in the concert when drummer Lars Ulrich joked that they should have sent the microphones to the Staples Center where the Grammys were being held.

Earlier today, the quartet confirmed the long-rumored North American stadium tour, announcing a trek with Avenged Sevenfold, Volbeat and Gojira each playing on select dates. See a list of all stops and more information here.

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