Gary Barlow's Christmas sing-along with his new TV co-stars Dannii Minogue and Martin Kemp was scuppered when comedian Alan Carr forced them to wear huge mouthguards to perform.
The Take That singer appears on the festive episode of Alan's Chatty Man show with Dannii and Martin, his fellow panellists on upcoming BBC programme Let It Shine.
The three singers and Alan decide to give a rendition of Take That's Back For Good.
But, keen to level the playing field, the comedian insists that the singers wear large mouth inserts for the performance.
They then struggle to hit the right notes in the hilarious skit, leaving it up to the audience to help get them get through the track.
Let It Shine will see Martin, Gary and Dannii - who are both former judges on The X Factor - search for the lead cast of a show based on Take That's music.
During their appearance on Chatty Man, Gary said judging vocalists on television is more difficult than it looks.
He said: "I used to sit in that studio at X Factor and it's so loud and the audience are so loud that sometimes you get to the end of the song and think, 'I didn't hear much of that.'
"So you have heard rehearsal and it was great and then you say, 'That was really good'. You watch it back later and go, 'What was I thinking?!' It's hard."
Gary also cleared up rumours of bad blood between him and X Factor boss Simon Cowell over Let It Shine.
"No. No, not at all, this whole thing came from the idea of the musical," he said.
"I thought wouldn't it be a great thing to put this on TV and let the audience decide who this band should be.
"When Dannii and me were talking about doing this show, I think at one point Dannii was like, 'I can't wait to come back to UK TV'.
"It just felt like a really good time to do this."
He continued: "Martin is my boy band. When I was a teenager I used to go down with my 50p and buy your singles. I thought what great experience he has got to bring to the panel."
Alan Carr's Christmas Chatty Man airs on Christmas Day at 10.30pm on Channel 4.