Sir Mick Jagger and Florence Welch are to duet on the Rolling Stones' hit track 'Gimme Shelter' as part of the band's '50 and Count' London 02 Arena show tomorrow night (29.11.12).
Florence will fly in from Luxembourg for the show and jet straight out to Germany afterward, to continue her group's European tour.
A source told the Daily Mirror newspaper: ''It is very, very tight indeed but it will definitely happen. You would never in a million years turn down the opportunity to duet with Mick on such an iconic song.''
Florence, 26, follows in the footsteps of R&B star Mary J. Blige who performed the song with the band on Sunday (25.11.12), while legendary singer-songwriter Eric Clapton is also lined up to appear at one of the anniversary shows.
The source added: ''Mary J. Blige did the female vocal part for the first show which blew the crowd away.
But Florence is determined to raise the bar even higher. It will be incredible.
''Eric [Clapton] is also taking part at some point, which will be historic too.''
Tickets for tomorrow's sold out show are being re-sold online for almost £5,000 and a spokesman for the band is upset at this inflated price.
They said: ''It's a shame fans have been prevented from buying tickets at the original price.''
After tomorrow's show, the band will head to the US for shows at the Barclay Center, New York City, on Saturday December 8 and the Prudential Center, New Jersey on December 13 and 15.