Britney Spears ditched the circus mime act for just one song during the opening concert of her world tour in New Orleans on Tuesday.

The pop princess pulled out all the stops for her 'live' big top-themed spectacular, which featured risque outfits, racy dance moves and show-stopping stunts.

But it all seemed to be compensating for one thing - that she was lip-synching as usual.

Although she did make an exception for the ballad Everytime, which she sang live - well, almost live.

With her backing track turned down to a minimum, Britney's shaky vocals were clearly audible as she warbled along while perched on a swing.

Britney was criticised for miming her way through her U.S and European televised performances before Christmas.

However, her team were quick to jump to her defense with the excuse that she needed to focus on her dance routines.

Listen to Britney singing 'Everytime' live in New Orleans