That's a bit of a stretch, Rihanna and Britney both performed on stage together and Rihanna was hardly better than Britney, let alone "10 times better."
The problem will always lie on the fact that Britney used to be 10 times better than she is now, whenever people see BRITNEY they expect a good ass performance and now they don't get half that which makes people think she's a ****** performer today.
Rihanna was a lot better than Britney when they performed together. Britney just don't give a f*ck, as you all will see when/if she performs with Will.