It was meant to be one of the Grammys' most moving moments: singing superstar Adele performing a heartfelt surprise tribute to the late, great George Michael.
As soon as she started, though, something seemed wrong. Adele was singing Michael's 1996 disco hit Fastlove, but stripped entirely of its pop production: Just her voice and a single, mournful piano note.
It sounded off, and she knew it. By the time the orchestra came in for the first chorus, she was so far off pitch that couldn't go on, stopping the performance in its tracks.
Watch Adele's tribute to George Michael in full here: pic.twitter.com/LmsfYFKMaG— Adele Daily (@AdeleDailyInfo) February 13, 2017
"I know it's live TV, I'm sorry," she interrupted before a series of expletives that were bleeped for viewers watching at home. "I need to start again. I f**ked up.
"I can't do it again like last year. I'm sorry for swearing and sorry for starting again. Can we please start it again? I'm sorry, I can't mess this up for him. I'm sorry. I'm sorry, Ken," she said, apparently referring to Grammys executive producer Ken Ehrlich.
Take two, and Adele started the song from the top once more. This time, she nailed it - but she was visibly upset at the end of the performance as the audience rose to their feet.
This isn't Adele's first hiccup at the Grammys, of course. Last year she performed the ballad All I Ask and was plagued with sound issues, giving an uncharacteristically bumpy performance.
That time, she carried on with the song, but speaking about the performance during an interview on The Ellen Show after the Grammys, Adele said that if she came up against similar issues in the future, she'd stop the show and start again.
Adele admitted she'd been "crying all day" after that botched performance, and Ehrlich said it had taken some work to woo her back to the Grammys stage for 2017, saying they'd "spent a year trying to make it up to her".
"It really threw her and I think what hurt us the most was ... just watching her face and seeing her trying to get through that with what had happened," he said.
Today's performance was no doubt especially important to Adele as she was a big fan of George Michael, even dressing as the singer for her birthday in 2015.
Michael, who rose to fame with the band Wham! and sold more than 100 million albums in his career, died on Christmas Day. He was 53.
And Grammys issues continued with the next performance of the night, a much-hyped collaboration between Lady Gaga and rockers Metallica.
Their song was marred by technical difficulties when Metallica singer James Hetfield's microphone appeared to be turned off for much of the song, leaving his parts of the song mute.