Charlotte Church performed an impromptu duet with Mercury Prize-winners Klaxons - but was interrupted by her mobile phone.
The singer teamed up with the guitar band after only a few minutes' practice when they were both booked to appear on BBC Radio 5 Live this afternoon.
But just as the group were about to begin, Charlotte's phone went off and she had to rifle through her bag to switch it off.
"I do apologise," the embarrassed singer told presenter Richard Bacon.
Charlotte and the band - who won the Mercury in 2007 for Myths Of The Near Future - had just the duration of a news bulletin to rehearse the song Twin Flames.
"This was very unexpected when I woke up this morning," she said before joining in on the acoustic track.
Afterwards the band's James Righton was impressed with the collaboration. "What are you doing next week? We've got a UK tour," he told her.