Christina Aguilera made a triumphant return on Thursday to the Latin Grammy Awards with an impressive costume-change performance at the Las Vegas event.The 40-year-old singer wore a long black dress for her opening number of Somos Nada with Colombian producer Julio Reyes Copello, 52, accompanying her on piano.Christina had her long scarlet hair down and earned applause from the audience at the MGM Grand Garden Arena when she held particularly high notes.