hollywoodreporter.com — Christina Aguilera joined her team on-stage to perform her 2003 single, "Fighter" on Monday's episode of NBC's The Voice. PHOTOS: 'The Voice' Contestants Volunteer at L.A. Food Bank It brought some levity to the night as she and coach Blake Shelton would have to make the difficult decision of cutting one their singers at the end of the quarterfinals performance episode.