Alison Goldfrapp was so starstruck she "couldn't get off the chair" or speak when she met Madonna.
The 'Rocket' singer admitted she finds it hard to meet other famous people - which can lead to her accidentally looking rude.
She explained: "I'm always quite starstruck. The first time I met Madonna, I couldn't actually get off the chair to shake her hand. It must have appeared really rude but it was because I was totally gobsmacked that she'd just walked in and made a beeline for me.
"I don't think I actually managed to get any words out; I just sort of froze and grinned inanely."
Alison also tipped Lady GaGa to replace Madonna as the "Queen of Pop", even though she finds the 'Telephone' singer's outrageous fashion choices more interesting than her music.
She added to Time Out magazine: "She's definitely taken the crown as the Queen of Pop. She's the new Madonna, I think. Lady Gaga is passionate about what she does - it's extreme and really good fun. Personally I think the clothes are a lot more interesting than the music. But who knows?
"She's obviously really talented, so it'll be interesting to see where her career goes. I think her success is also to do with timing: we all want something to escape to."
Goldfrapp - which also includes multi-instrumentalist Will Gregory - released their latest album 'Head First' last month.