The 90s girl band - made up of Mel, Victoria Beckham, Geri Halliwell, Emma Bunton and Mel C - are seeing their hit songs turned into West End stage show, entitled 'VIVA FOREVER!' and Mel admits they've been blown away by the vocal talents of the cast.
She quipped: ''They sing it better than us.
To which, Mel C replied: ''Well that's not hard!''
All the girls have been impressed with the musical - which has been written and produced by Jennifer Saunders and Judy Craymer respectively - and Victoria is hoping the show inspires another generation of women to embrace the group's Girl Power motto.
Speaking at the launch of the musical at London's St Pancras Renaissance Hotel, the mother-of-four told BANG Showbiz: ''I think we're going to be introducing a whole new generation to Girl Power. What we do individually is really empowering and collectively. And I'm hoping there's going to be a whole load of new people coming on board. But we're just so excited about the whole thing.''
Emma - who has two children, Beau, four, and 13-month-old Tate - also said she is excited about her eldest son being able to see the show.
She said: ''I think this is mainly for our fans. They have been so supportive and just brilliant, so thank you. And my little boy doesn't know who we are so I can't wait for him to see this! Then he can see what mummy does.''
'VIVA FOREVER!' opens for previews at London's Piccadilly Theatre on November 27 and tickets are now on sale.
For more information go to www.VivaForeverTheMusical.com.