Lady Gaga and Metallica performance besieged by tech problems at Grammys

Joanne might've surprised fans by stripping away its maker's signature brand of electropop in favor of a fresh, rock-inspired sound, but Lady Gaga's duet with Metallica at Sunday's Grammys reaffirmed the "John Wayne" singer can hold her own against the genre's heaviest hitters — despite some technical difficulties.

One week after taking the biggest stage on television as the Super Bowl LI halftime show headliner and announcing a worldwide tour, Gaga — clad in leather, fishnets, and a Metallica T-Shirt — joined the iconic metal band to perform "Moth Into Flame" at Los Angeles' Staples Center on a stage complete with flashing lights and flames.

But shortly after the song began, it became evident that James Hetfield's microphone wasn't working. After singing a few unamplified lines, Hetfield joined Gaga at her mic until his was fixed.

After their performance, Hetfield appeared to kick over his mic stand and toss his guitar off stage.

The performance was announced in a television commercial that aired Monday night on CBS. During a Wednesday interview with Zane Lowe, Gaga said her A Star Is Born director and costar, Bradley Cooper, facilitated the Metallica collaboration.

" I was at Bradley's house with Lars [Ulrich] and we were just hanging out. He's amazing," said Gaga, referencing the rock band's co-founder and drummer. "I went to see them live, I've seen them a couple times live, but I saw them recently… and we were watching the show and I'll tell you something, those guys play better than they've played in their whole lives."

This year's gig marks Gaga's third straight year on the Recording Academy's stage, having sung "Cheek to Cheek" (a cover lifted from their Grammy-winning album of the same name) alongside Tony Bennett in 2015, followed by her show-stopping medley tribute to the late David Bowie at the 2016 Grammys ceremony.

Gaga has six competitive Grammys to her name, while Metallica, nominated again this year for Best Rock Song ("Hardwired"), have eight.

A self-admitted fan of metal music, Gaga, who performed in a Led Zeppelin cover band as an up-and-coming singer, belted an acapella version of the group's "Black Dog" on The Howard Stern Show last October. She also included a track called "Heavy Metal Lover" on her 2011 studio set Born This Way, an album that features sonic inspiration from 1980s arena rock.

For a full list of Grammy winners, click here.