Sir Paul McCartney forgets the lyrics to Hey Jude.
The Beatles musician has been singing the 1968 single for over 40 years, but although he sometimes forgets the words, says crowds don't mind.
He said: "It's funny. I sometimes forget those. It's a devilish lyric. I occasionally do forget them. But the great thing is, I used to panic about that, but I realise now that the audiences don't mind.
"In fact, they quite like it. They're at the show where I forgot the words, and it makes that show special."
Paul is playing at the Opening Ceremony of the Olympic games and although he's not particularly nervous, hopes he doesn't make any mistakes on stage.
He joked to ShortList magazine: "Generally I don't [get nervous]. But having said that, you never quite know. You can do something such as the Jubilee or the Olympics and get the old collywobbles.
"Oh God, that'd be good, wouldn't it? Make a mistake at the Olympics. 'Hi there. Listen, welcome to Britain. I just wanted to stop the song, just for a minute. We'll start again.'"