Coldplay wowed the crowd at Glastonbury, leaving no question about their status as one of the world's best bands.
But some of Chris Martin's fans did have a question after their performance - what was up with that piano?
The rocker was sat playing the instrument towards the opening of their set and many viewers noticed his unusual rocking motion as he tinkled the keys.
However, that question might have been answered when Chris launched into Everglow from new album A Head Full Of Dreams, and quickly discovered there was a technical hitch.
He said: "What's going on, man? One of us is really out of tune."
After stopping the song to discuss the issue with the rest of his band, he said: "That's a terrible problem live at Glastonbury, shall we skip to the next song?"
He then decided to continue the song alone, explaining: "I can do it. Having introduced the rest of the best band in my lifetime, they've left me on my own.
"There's something wrong with the piano but we can muster through."
Maybe that was it then?