Rihanna was joined by Katy Perry, both looking as though they were sharing a single brain cell between them, on the front row of Karl Lagerfield's ready to wear Spring/Summer 2010 collection.

And Katy managed to drag herself away from new lover Russell Brand, who she'd spent the last three days holed up with at his Hampstead home, to leave him behind in London. 

So it was just the one arse on show (sorry)...