Mash-ups the hot circa-2002 underground trend of marrying disparate tracks are entertaining because they force collaborations that would never materialize in the corporate world. Maybe that's why this label-sanctioned pairing comes off like a sanitized nonevent. While Jay-Z delivers a knockout punch on ''Dirt Off Your Shoulder/Lying From You,'' nothing on this forgettable effort compares to Jigga fronting the Beatles on Danger Mouse's imaginative Grey Album bootleg.

