Gaga and Metallica performed "Moth Into Flame" from the latter band's latest album "Hardwired... to Self-Destruct". Lady Gaga belted clearly into the microphone, but James Hetfield's microphone wasn't working, and he didn't seem to notice for several verses.
Gaga even launched herself into the sellout audience for some crowd surfing at one point, a throwback to Metallica concerts of yore.
It wasn't without its technical difficulties, but the group fought through admirably.
On stage, she changed into a similar ensemble, this time switching out the constricting crop top from the red carpet with a Metallica concert tee and studded leather shorts. He's unbelievable. I went to see them live.
Gaga switches genres so much, we basically forgot who she actually is.
She said: "I can't do it again, not after a year ago, I can't mess this up for him".
On Feb. 12, the best and brightest names in music will be attending the Grammy Awards in Los Angeles, California, one of the biggest music events of the year.
They may have suffered a setback, but Lady Gaga and Metallica still owned the stage.
LADY Gaga's Grammy performance with Metallica was another victim of live TV - as one of their mics failed to work.
Singer Lady Gaga and Hollywood star John Travolta proved that they have all the right moves when hitting the dance floor at the Grammy after-party.
While she was nearly tripping over his mic stand, then crowd surfing, Hetfield sang, with mixed success, but clearly not enough to satisfy him.