In front of a star-studded aud i enc e tha t inc lude d Jennifer Lopez, Heidi Klum and Kate Moss, Spears, 26, joined the 50-year-old Material Girl on stage for the Los Angeles leg of her Sticky And Sweet tour at the Dodgers Stadium. Britney has already made an appearance on the tour but in video form, when she shot a short film - which was played as a backdrop for part of the multi-million-pound show. This time she stood alongside her ageing idol while performing Human Nature.