Take a listen ... Christina's song clearly samples from a 1968 latin soul tune called "Hippy Skippy Moon Strut" (aka "I'll Be a Lucky Man) by Dave Cortez and the Moon People. Gotta love that name.
According to the federal lawsuit, filed in New York, TufAmerica purchased exclusive rights to 'Hippy Skippy' in 2004 ... however Sony Music -- Christina's label -- made a deal with Codigo Music and the Clyde Otis Music Group to use the song. Aguilera is not named as a defendant in the suit.
TufAmerica is asking the court to declare it the rightful owner of the groovy '60s hit ... and to void the other publishers' claims on the song. The company also wants damages -- as in money.