Sir Paul McCartney has been told to keep the noise down at a concert in Rome for fear of disturbing the Pope.
The European leg of the tour kicks off in Paris
The former Beatle is due to perform a free three-hour show outside the Coliseum in May and crowds of more than 300,000 are expected.
But the gig - the biggest of Sir Paul's career - could also be the quietest.
Organisers are considering dropping some of the rock numbers, including Back In The USSR and Live and Let Die.
We don't want to tone down the rock and roll element in the set - we reckon the Pope may actually enjoy a boogie
Sir Paul McCartney's spokesman
They are worried that the 82-year-old Pope will be kept awake by the noise.
"We have been advised by Italian contacts that the show could keep His Holiness the Pope up all night," said tour promoter Barrie Marshall.
The warning, he said, had not come from the Vatican itself
but from the tour's promoters in the Italian capital.
"Obviously we do not want to cause any offence or sleeplessness to His Holiness and, because of the closeness of The Vatican to the show at the Coliseum, we are now considering our position on performing loud rock songs."
The Vatican is near to where the gig is being held
Sir Paul's first European tour for a decade includes at least 15 Beatles tracks such as Lady Madonna, All My Loving and I Saw Her Standing There.
If changes are made, Sir Paul may have to add them to his acoustic set or just play ballads.
"We don't want to tone down the rock and roll element in the set - we reckon the Pope may actually enjoy a boogie," said a spokesman for Sir Paul.
"But we don't want problems with the neighbours."
Sir Paul's European tour kicked off in Paris this week and reaches the UK this weekend.
He will also visit Spain, Belgium, Germany, Russia, Hungary, Austria, the Netherlands and Ireland.