When you have a voice as distinctive as Christina Aguilera's, there's no disguising it - even under a floppy hat, sunglasses and ill-fitting denim jacket.

The pop singer was a guest on Jimmy Fallon's show the other day, and the pair decided to go busking in the New York subway to celebrate her new album 'Liberation' being released.

It wasn't long before a crowd gathered as they played Aretha Franklin's 'Think' - it's not every day you hear a busker with a voice like that, after all.

After revealing their not-so-cunning disguises to the huge audience, they then knocked out an acoustic version of her song 'Fighter'.

Watch it below: