Beyonce Knowles insists she feels "sick" with jealousy whenever she hears a great track by a rival artist. The Crazy In Love beauty tries to be philosophical about the fact she can't always be the best, using her competitive streak to improve her own work - but it isn't easy. She says, "When I hear a great new record, especially when it's by someone that I respect and admire, then a part of me is like, 'Why didn't I think of that? Why didn't I make that record?' "It makes you sick but in a way it can be a great thing. It makes you want to go back to the lab and start writing again. Maybe it will inspire you to work a little harder."