The show must go on, and in Paris this week that meant convincing a mezzo-soprano who came to enjoy Handel's "Messiah" to hastily take the stage after a soloist bowed out halfway through the concert.

Adele Charvet, who had never before sung the famed choral work, was in the audience at the Radio France Auditorium on Tuesday night for the concert being led by her friend, the conductor Valentin Tournet.

All was going well until the intermission, when the South Korean countertenor David DQ Lee informed Tournet that he was done for the night.

"During the break I ran into the stage manager, who told me the countertenor couldn't sing another note and asked me to go backstage," Charvet told AFP on Wednesday.

Stretching out the intermission by 15 minutes gave her time to run through her parts, but hardly any time to warm up her vocal chords and no time to dress up - she sang in her jeans.

"It went better than I thought... the audience was incredibly encouraging and happy," Charvet said.

The concert will be broadcast on France Musique radio on November 5.