'Monty Python Live (Mostly): One Down, Five To Go' will feature a cameo from Stephen Hawking.
One of the surprises planned for the iconic comedy troupe's final hurrah, which kicks off tomorrow night (01.07.14) at London's O2 Arena with the first of 10 live shows, is a special appearance from the pioneering scientist.
Eric Idle explained: ''It would be folly to try and switch it up and do something else at this age. But we've changed it up a bit and put some surprises in. Stephen Hawking is in the show and is coming to the performance too. He was asked and within one minute, he said yes!''
The gang are performing together for the first time in 40 years, without sixth Python Graham Chapman, who died of cancer in 1989, and hinted there will be plenty more surprise cameos in store for fans.
Michael Palin teased: ''We might have certain celebrities... There's a sketch which has potential [famous guests] in depending on who turns up on the night.''
Meanwhile, John Cleese revealed David Walliams will be on hand to host an unconventional red carpet for fans during the final ever 'The Last Night Of The Pythons' show, which will be broadcast in 1800 cinemas around the world and be shown live on UKTV Gold.
He said: ''A lot of Python fans like to get dressed up in silly costumes, at the O2 there'll be the 'dead carpet' where people can come and be interviewed. David Walliams is broadcasting that on the last night. It's like a crazy party!''
Legions of comedy fans the world over will be disappointed to hear the July 20 show is definitely the last.
John added: ''It really is the last show and I think we all feel very content with it... I certainly thought it might be fun to go and do America, but the more I thought about it the more I didn't really want to.
''I think it's much better to do it really well once in England, where it started, and leave it at that.''
Eric concluded: ''It's exciting to be able to say goodbye publicly in one show, that's really exciting. The Beatles didn't get a chance to do that. I think that's rather lovely, I'm very grateful it's come to be.''
Michael, John and Eric were joined by Terry Jones and Terry Gilliam at a press conference announcing the biggest live event of 2014. New tickets go on sale tomorrow, while today sees the release of the complete collection of all nine albums, 'Monty Python's Total Rubbish', by Virgin EMI Records.